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Business

Billable Hours Calculator

Estimate billable hours after non-billable time.

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Business

Break-Even Calculator

Break-even units and revenue from costs and price.

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Business

Capacity Utilization Calculator

Used capacity as a percent of available hours.

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Business

Contribution Margin Calculator

Contribution dollars and margin percent.

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Business

Hourly Rate From Salary Calculator

Billing rate from target salary and yearly billable hours.

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Business

Invoice Terms Days Calculator

Show calendar days until payment under Net terms.

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Business

Price From Margin Calculator

Selling price from cost and desired margin percent.

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Chemistry

Atom Calculator (Neutrons)

Find the number of neutrons from mass number and atomic number.

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Chemistry

Atom Calculator (Protons)

Number of protons equals the atomic number Z.

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Chemistry

Dilution Calculator

Solve V2 from C1V1=C2V2.

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Chemistry

Mole Calculator

Convert among mass, moles, and particle count using molar mass.

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Construction

Circle Footage Cost Calculator

Cost of a circular area from radius and cost per ft².

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Construction

Concrete Ark Volume Calculator

Volume of a semicircular (arch) vault: half-cylinder approximation.

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Construction

Concrete Round Slab Volume Calculator

Volume of a circular slab from diameter and thickness.

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Construction

Concrete Steps Calculator

Approximate solid concrete volume for a straight staircase.

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Construction

Concrete Volume Calculator

Rectangular pour volume from length, width, and thickness.

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Construction

Decagon Footage Cost Calculator

Cost of a regular decagon from side length and cost per ft².

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Construction

Decking Boards Calculator

Board count across a width for decking.

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Construction

Drywall Sheets Calculator

Drywall sheets from wall area, waste, and sheet size.

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Construction

Feet and Inches Calculator

Convert feet + inches into total inches, decimal feet, meters, and centimeters.

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Construction

Fence Material Calculator

Posts, panels, and rails for a straight fence run.

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Construction

Footage Cost Calculator

Total cost from area and cost per square unit.

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Construction

Heptagon Footage Cost Calculator

Cost of a regular heptagon from side length and cost per ft².

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Construction

Hexagon Footage Cost Calculator

Cost of a regular hexagon from side length and cost per ft².

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Construction

Meters and Centimeters Calculator

Convert meters + centimeters into total cm, decimal meters, feet, and inches.

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Construction

Mulch Annulus Calculator

Mulch volume for a ring (annulus) bed between two radii.

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Construction

Mulch Calculator

Mulch volume from known coverage area and depth.

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Construction

Mulch Circle Border Calculator

Mulch volume for a circular border (ring) around a radius.

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Construction

Mulch Circle Volume Calculator

Mulch volume for a circular bed.

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Construction

Mulch Rectangle Border Calculator

Mulch volume for a rectangular border (picture-frame) bed.

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Construction

Mulch Rectangle Calculator

Mulch volume for a rectangular bed.

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Construction

Mulch Square Calculator

Mulch volume for a square bed.

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Construction

Mulch Trapezoid Calculator

Mulch volume for a trapezoid-shaped bed.

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Construction

Mulch Triangle Calculator

Mulch volume for a triangular bed.

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Construction

Octagon Footage Cost Calculator

Cost of a regular octagon from side length and cost per ft².

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Construction

Paint Estimator Calculator

Estimate paint gallons for walls (length as perimeter).

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Construction

Pentagon Footage Cost Calculator

Cost of a regular pentagon from side length and cost per ft².

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Construction

Rectangle Footage Cost Calculator

Cost of a rectangular area from length, width, and cost per ft².

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Construction

Roof Pitch Calculator

Pitch ratio and angle from rise and run.

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Construction

Square Footage Cost Calculator

Cost of a square area from side length and cost per ft².

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Construction

Stair Stringer Calculator

Riser count, actual rise, and total run for stairs.

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Construction

Triangle Footage Cost Calculator

Cost of a triangular area from base, height, and cost per ft².

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Converters

Angle Converter

Degrees, radians, and gradians (mode 0–3).

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Converters

Area Converter

Convert between square meters, acres, hectares, square feet, and more.

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Converters

Base Converter

Convert integers between binary, octal, decimal, and hexadecimal.

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Converters

Data Storage Converter

Convert among B, KB, MB, GB, TB (binary).

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Converters

Download Speed Converter

Convert download/transfer rates between bit and byte based units.

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Converters

Energy Converter

Convert joules, calories, watt-hours, BTU, and electronvolts.

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Converters

Force Converter

Convert newtons, kilogram-force, pound-force, and dynes.

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Converters

Fuel Economy Converter

MPG ↔ L/100km (mode 0=mpg→L/100km, 1=reverse).

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Converters

Length Converter

Convert meters, kilometers, miles, feet, inches, and more.

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Converters

Megabytes Converter

Convert data sizes between bits, bytes, KB/MB/GB (decimal SI) and KiB/MiB/GiB.

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Converters

Power Converter

Convert watts, kilowatts, horsepower, and BTU per hour.

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Converters

Pressure Converter

Convert pascals, bars, atmospheres, psi, and torr.

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Converters

Roman Numerals Converter

Convert between Arabic numbers (1–3999) and Roman numerals.

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Converters

Temperature Converter

Convert between Celsius, Fahrenheit, and Kelvin.

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Converters

Time Converter

Convert seconds, minutes, hours, days, weeks, and years.

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Converters

Velocity Converter

Convert speed between m/s, km/h, mph, knots, and ft/s.

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Converters

Volume Converter

Convert liters, milliliters, gallons, cups, and cubic meters.

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Converters

Weight Converter

Convert kilograms, grams, pounds, ounces, and stones.

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Cooking

Bakers Percentage Calculator

Baker's percent of an ingredient relative to flour.

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Cooking

Cake Pan Converter

Compare common cake pans by batter capacity (approximate cups).

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Cooking

Cooking Ingredient Converter

Convert common baking ingredients between volume and weight.

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Cooking

Cooking Measurement Converter

Convert teaspoons, tablespoons, cups, pints, quarts, and liters.

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Cooking

Oven Temperature Calculator

Oven °C ↔ °F (mode 0=C→F, 1=F→C).

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Cooking

Recipe Cost Calculator

Sum ingredient costs for a recipe.

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Cooking

Recipe Scale Calculator

Scale an ingredient amount to a new serving count.

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Cryptography

AES-GCM Encrypt/Decrypt

Encrypt or decrypt with AES-256-GCM and a password-derived key (PBKDF2). Learning/interoperability tool—not a replacement for audited secret management.

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Cryptography

HMAC Calculator

Compute or verify HMAC-SHA-256/384/512 with a UTF-8 or Hex key. Runs entirely in your browser via Web Crypto.

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Cryptography

PBKDF2 Key Derivation

Derive a key from a password with PBKDF2-SHA-256/512, salt, and iteration count. Educational interoperability tool—not account-storage guidance.

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Cryptography

Password/Passphrase Generator

Generate passwords or passphrases with CSPRNG-backed unbiased selection, character groups, exclusions, and a live entropy estimate.

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Cryptography

SHA Hash Calculator

Compute SHA-256, SHA-384, SHA-512, or legacy SHA-1 digests from text or a local file. Output Hex and Base64 in your browser only.

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Cryptography

Secure Random Generator

Generate cryptographically secure random bytes, Hex, Base64, UUIDs, or unbiased integers using crypto.getRandomValues().

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Date Time

24-Hours Clock Calculator

Convert a 12-hour clock time to 24-hour format.

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Date Time

Age Calculator

Calculate age in years, months, and days from a birth date.

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Date Time

Age On Date Calculator

Exact age in years, months, and days on a target date.

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Date Time

Business Days Add Calculator

Add N business days (Mon–Fri) to a start date.

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Date Time

Date Calculator

Add or subtract days from a starting date.

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Date Time

Days Ago Calculator

Find the calendar date N days before today.

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Date Time

Days From Today Calculator

Find the calendar date N days after today.

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Date Time

Days Until Calculator

Count whole days from today until a target date.

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Date Time

Hours Ago Calculator

Find the date/time N hours before now.

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Date Time

Hours Calculator

Compute the number of hours between two date/times.

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Date Time

Hours From Now Calculator

Find the date/time N hours from now.

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Date Time

How Long Until Calculator

Show days, hours, and minutes remaining until a target.

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Date Time

Minutes Ago Calculator

Find the date/time N minutes before now.

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Date Time

Minutes From Now Calculator

Find the date/time N minutes from now.

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Date Time

Months Ago Calculator

Find the calendar date N months before today.

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Date Time

Months From Now Calculator

Find the calendar date N months after today.

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Date Time

Time Calculator

Add hours and minutes to a starting date/time.

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Date Time

Timezone Offset Calculator

Local hour from UTC hour and offset, wrapped to 0–24.

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Date Time

Weeks Ago Calculator

Find the calendar date N weeks before today.

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Date Time

Weeks From Now Calculator

Find the calendar date N weeks after today.

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Date Time

Work Hours Calculator

Hours worked between start/end times with break.

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Design

Aspect Ratio Calculator

Ratio and simplified W:H of a rectangle.

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Design

DPI PPI Calculator

Pixels per inch from pixel size and print size.

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Design

Golden Ratio Calculator

Longer or shorter segment from golden ratio (mode 0=longer, 1=shorter).

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Design

PX REM Calculator

Convert px ↔ rem (mode 0=px→rem, 1=rem→px).

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Design

Resolution Scale Calculator

Scaled pixel dimensions for 2× / 3× assets.

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Design

Screen Diagonal Calculator

Diagonal from width and height (same units).

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Education

Final Grade Needed Calculator

Score needed on the final to hit a course goal.

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Education

Grade Curve Calculator

Linear map of a score from one scale to another.

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Education

Points Needed Calculator

Points needed on the next assessment to hit a goal percentage.

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Education

Reading Time Calculator

Minutes to read a word count at a given WPM.

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Education

Semester GPA Calculator

GPA from up to four courses (grade points × credits).

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Education

Weighted Grade Calculator

Course grade from up to four weighted components.

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Encoding

Base64 Encoder/Decoder

Encode or decode Base64 with UTF-8-safe conversion and clear errors for invalid data. Runs entirely in your browser.

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Encoding

CRC-32 Checksum

Compute a CRC-32 checksum over text. Non-cryptographic—use for integrity checks against accidental corruption only.

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Encoding

Text ↔ Hex Converter

Convert between UTF-8 text and hexadecimal byte strings using TextEncoder/TextDecoder in your browser.

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Encoding

URL Encoder/Decoder

Encode or decode URL component strings with percent-encoding suitable for query values and path segments.

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Everyday

Event Countdown Calculator

Day difference between two day-numbers (e.g. ordinal dates).

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Everyday

Pomodoro Planner Calculator

Total session time from Pomodoro counts and break lengths.

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Everyday

Sleep Duration Calculator

Hours slept from bedtime and wake time.

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Everyday

Steps Distance Calculator

Distance from step count and stride length.

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Everyday

Water Intake Calculator

Rough daily water liters from body weight (35 ml/kg).

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Finance

APY Calculator

Convert nominal APR and compounding frequency into annual percentage yield.

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Finance

Cash Flow to Debt Ratio Calculator

Measure operating cash flow relative to total debt.

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Finance

Cash Ratio Calculator

Compare cash and cash equivalents to current liabilities.

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Finance

Certificate of Deposit Calculator

Estimate CD maturity value with compound interest (workbook: Certificate of Deposit).

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Finance

Compound Annual Growth Rate (CAGR) Calculator

Average annual growth rate between a start and end value.

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Finance

Compound Interest Rate Calculator

Solve for the nominal rate that grows principal to a future value.

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Finance

Current Ratio Calculator

Assess short-term liquidity: current assets ÷ current liabilities.

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Finance

DCA Investment Calculator

Future value of regular fixed deposits (DCA).

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Finance

Debt Payoff Calculator

Months and interest to clear a balance at a fixed payment.

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Finance

Dividend Calculator

Compute annual dividend income and yield from shares owned.

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Finance

Dividend Discount Model Calculator

Value a stock from next year's dividend, required return, and growth (Gordon model).

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Finance

Dividend Payout Ratio Calculator

See what share of net income is paid out as dividends.

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Finance

EBITDA Calculator

Estimate earnings before interest, taxes, depreciation, and amortization.

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Finance

Earnings per Share (EPS) Calculator

Compute basic EPS (workbook name: Earnings per Share (EPS)).

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Finance

Effective Interest Rate Calculator

Effective annual rate from a nominal rate and compounding frequency.

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Finance

Equivalent Annual Rate (EAR) Calculator

Equivalent annual rate (EAR) from nominal rate and compounding.

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Finance

Expense Ratio Calculator

Fund expense ratio as annual expenses over average assets.

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Finance

Expense Ratio Calculator (Cost of ETF)

Estimate the dollar cost of an ETF expense ratio over time.

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Finance

Forward Rate Calculator

Implied forward rate between two spot-rate maturities.

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Finance

Future Value Calculator

Project how a present amount grows at a periodic rate.

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Finance

Inflation Calculator

See future nominal value and today's purchasing power after inflation.

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Finance

Investment Calculator

Project future value of a principal with regular deposits and compound growth.

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Finance

Loan Comparison Calculator

Compare payments and totals for two loans.

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Finance

Net Profit Margin Calculator

Net profit margin from net income and revenue.

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Finance

Refinance Break-Even Calculator

Months until closing costs are recovered by payment savings.

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Finance

Return on Ad Spend (ROAS) Calculator

Measure revenue generated per dollar of ad spend (workbook: Return on Ad Spend (ROAS)).

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Finance

Return on Investment (ROI) Calculator

Calculate ROI as percent gain relative to cost (workbook: Return on Investment (ROI)).

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Finance

Rule of 72 Calculator

Years to double at a constant annual rate.

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Finance

Salary Calculator

Break an annual salary into monthly, biweekly, weekly, and hourly pay.

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Finance

Salary to Hourly Calculator

Convert annual salary to an equivalent hourly wage.

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Finance

Sales Tax Calculator

Compute sales tax and total price from a pre-tax amount.

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Finance

Savings Goal Calculator

Monthly deposit needed to reach a goal.

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Fitness

BMI Calculator

Body mass index from weight and height (Metric or US units).

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Fitness

BMR Calculator

Basal metabolic rate via the Mifflin–St Jeor equation.

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Fitness

Body Fat Calculator

Estimate body-fat percentage with the U.S. Navy method.

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Fitness

Calorie Calculator

Daily calorie target from BMR, activity, and goal.

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Fitness

Calories Burned Calculator

Estimate calories burned from MET, weight, and duration.

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Fitness

Heart Rate Zones Calculator

Rough training zones from max HR or 220−age.

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Fitness

Ideal Weight Calculator

Ideal body weight estimate using the Devine formula.

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Fitness

Lean Body Mass Calculator

Lean body mass estimate using the Boer formula.

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Fitness

Macro Split Calculator

Grams of protein, carbs, and fat from calorie share percents.

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Fitness

Maintenance Calorie Calculator

Daily maintenance calories (TDEE) from BMR and activity.

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Fitness

One Rep Max Calculator

Estimated 1RM using the Epley formula.

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Fitness

Pace Calculator

Running/walking pace per unit distance from time and distance.

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Fitness

Pace to Race Time Calculator

Finish time from pace and distance.

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Fitness

Protein Target Calculator

Daily protein grams from body weight and g/kg factor.

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Geometry

Area

Rectangle area from length and width.

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Geometry

Circle

Circle area, circumference, and diameter from radius.

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Geometry

Cone Calculator

Cone surface and volume.

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Geometry

Cylinder Calculator

Cylinder surface and volume.

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Geometry

Distance

Euclidean distance between two points in the plane.

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Geometry

Ellipse Area Calculator

Area of an ellipse from semi-axes a and b.

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Geometry

Polygon Angles Calculator

Interior sum and each exterior angle for a regular polygon.

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Geometry

Pythogorean Theorem

Hypotenuse of a right triangle from legs a and b (workbook spelling).

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Geometry

Regular Polygon Area Calculator

Area of a regular polygon from sides and side length.

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Geometry

Sphere Calculator

Sphere surface area and volume from radius.

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Geometry

Surface

Surface area of a rectangular box.

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Geometry

Volume

Volume of a rectangular box.

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Home

AC BTU Calculator

Rough cooling BTU from room size (≈20 BTU/ft²).

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Home

Energy Cost Calculator

Electricity cost from kWh and rate.

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Home

Flooring Quantity Calculator

Flooring area with waste and box count.

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Home

Paint Coverage Calculator

Paint gallons from wall area, coats, and coverage rate.

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Home

Wallpaper Rolls Calculator

Rolls needed from wall area and roll coverage.

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Math

Binary Calculator

Convert an integer to binary (and hex) representation.

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Math

Euler Totient Calculator

Compute Euler's totient φ(n) for bounded educational integers—the count of integers up to n that are coprime to n.

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Math

Exponent Calculator

Raise a base to a power: base^exponent.

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Math

Extended GCD / Modular Inverse

Compute the extended GCD, Bézout coefficients, and modular inverse when it exists. Educational BigInt calculator.

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Math

Fraction Calculator

Simplify fractions or add, subtract, multiply, and divide them.

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Math

Function Grapher

Plot y = f(x) over a chosen domain, with an optional second curve.

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Math

GCD and LCM Calculator

Greatest common divisor and least common multiple of two integers.

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Math

Hex Calculator

Convert an integer to hexadecimal (and binary).

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Math

Linear Equation Calculator

Solve a x + b = c for x.

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Math

Log Base 2 Calculator

Compute the base-2 logarithm of a positive number.

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Math

Log Calculator

Compute a logarithm for a chosen base (default base 10).

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Math

Matrix 2×2 Calculator

Determinant and inverse of a 2×2 matrix.

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Math

Modular Exponentiation Calculator

Compute base^exponent mod modulus with BigInt square-and-multiply. Useful for understanding RSA-style operations (educational).

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Math

Percent Given Value Calculator

Find what percent one number is of another.

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Math

Percentage Calculator

Find a percent of a number, reverse percentages, and percent change.

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Math

Percentage Error Calculator

Relative error between experimental and theoretical values as a percent.

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Math

Permutation and Combination Calculator

Compute P(n, r), C(n, r), and n! for non-negative integers.

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Math

Prime Factors Calculator

Factor an integer into primes.

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Math

Proportion Calculator

Solve a/b = c/x for x.

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Math

Quadratic Equation Calculator

Solve ax² + bx + c = 0 for real roots.

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Math

Remainder Calculator

Divide two numbers and show remainder (modulo) and quotient.

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Math

Rounding Calculator

Round a number to a chosen number of decimal places.

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Math

Scientific Calculator

Keyboard-first scientific calculator with DEG/RAD trig, 2nd functions, memory, history, and display modes.

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Math

Significant Figures Calculator

Round a number to a given count of significant figures.

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Math

Toy RSA Demonstrator

Walk through tiny RSA with user-provided small primes: n, φ(n), e, d, and encrypt/decrypt steps. Educational only—not production keys.

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Math

Two's (2's) Complement Calculator

Show the two's-complement binary and hex encoding of a signed integer.

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Math

Value Given Percent Calculator

Find P% of a whole number.

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Other

Aspect Fit Calculator

Scale an image to fit inside a box (contain).

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Other

Dice Roller

Roll one or more dice with a chosen number of sides.

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Other

Download Time Calculator

Estimate download duration from file size and link speed.

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Other

GPA Planning Calculator

GPA needed in remaining credits to hit a target cumulative GPA.

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Other

Gas Mileage Calculator

Miles per gallon (and L/100 km) from distance and fuel used.

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Other

Grade Calculator

Weighted average grade from up to five score/weight pairs.

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Other

Height Calculator

Convert height between centimeters and feet/inches.

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Other

IP Subnet Calculator

IPv4 network, netmask, broadcast, and host count from CIDR.

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Other

Password Entropy Calculator

Bits of entropy from length and charset size (with presets).

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Other

Pregnancy Calculator

Estimated due date and gestational age from LMP (Naegele).

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Other

Prime Number Calculator

Check whether an integer is prime.

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Other

Random Number Generator

Generate a random integer in an inclusive min–max range.

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Other

Text Stats Calculator

Live character, word, sentence, line, and reading-time stats.

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Other

Tip For Groups Calculator

Tip and per-person total for a shared bill.

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Other

Unit Price Compare Calculator

Compare unit prices of two packages.

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Personal Finance

50/30/20 Budget Calculator

Split income into needs, wants, and savings.

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Personal Finance

Amortization Calculator

Period-by-period payment schedule with principal, interest, balance, and CSV download.

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Personal Finance

Auto Loan Calculator

Vehicle loan payment with period schedule, totals, and CSV download.

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Personal Finance

Compound Interest Calculator

Compound interest future value and interest earned.

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Personal Finance

Emergency Fund Calculator

Target cash reserve from months of expenses.

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Personal Finance

Finance Charge Calculator

Total finance (interest) charge on an amortizing loan.

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Personal Finance

Interest Calculator

Simple interest amount and total repayment.

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Personal Finance

Investment Calculator

Project growth of savings with regular deposits (Personal Finance).

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Personal Finance

Loan Calculator

Fixed payment, total paid, and interest for an amortizing loan.

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Personal Finance

Mortgage Calculator

Monthly mortgage payment plus a full amortization schedule and CSV download.

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Personal Finance

Raise Impact Calculator

New salary and monthly increase from a percent raise (pre-tax).

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Personal Finance

Rent vs Buy Calculator

Rough cash comparison of renting vs owning over N years.

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Personal Finance

Simple Interest Calculator

Simple interest I = P r t and total amount.

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Personal Finance

Subscription Cost Calculator

Annualize monthly subscription costs.

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Physics

Acceleration Calculator

Average acceleration from change in velocity and time.

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Physics

Angular Resolution Calculator

Diffraction-limited angular resolution θ ≈ 1.22 λ / D.

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Physics

Angular Velocity Calculator

Compute average angular velocity ω = θ / t.

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Physics

Aperture Area Calculator

Area of a circular aperture from its diameter.

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Physics

Bernoulli Equation Calculator

Solve for downstream pressure P₂ along a streamline.

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Physics

Brewster's Angle Calculator

Polarizing angle θ_B = arctan(n₂ / n₁).

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Physics

Buoyancy Calculator

Buoyant force F_b = ρ V g (Archimedes).

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Physics

Capacitance Calculator

Capacitance from charge and voltage: C = Q/V.

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Physics

Cylindrical Pipe Flow Rate Calculator

Volumetric flow Q = π r² v for a full circular pipe (workbook name).

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Physics

Density Calculator

Density ρ = m / V.

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Physics

Displacement (distance traveled) Calculator

1D displacement under constant acceleration: s = u t + ½ a t².

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Physics

Drag Equation Calculator

Quadratic drag force F_d = ½ ρ v² C_d A.

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Physics

E = mc² Calculator

Mass–energy equivalence E = m c² (workbook: E = mc²).

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Physics

Electric Power Calculator

Power from voltage and current: P = V I.

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Physics

Force Calculator

Newton's second law: F = m a.

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Physics

Free Fall Calculator

Distance and impact speed for free fall from rest: s = ½ g t², v = g t.

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Physics

Frequency Wavelength Calculator

Convert frequency ↔ wavelength (mode 0: f→λ, 1: λ→f).

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Physics

Friction Calculator

Kinetic/static friction magnitude F = μ N.

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Physics

Froude Number Calculator

Froude number Fr = v / √(g L).

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Physics

Gravitational Force Calculator

Newton's law of universal gravitation between two masses.

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Physics

Hooke's Law Calculator

Spring force F = k x.

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Physics

Hydraulic Pressure Calculator

Fluid pressure from force on a piston area.

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Physics

Hydraulic Radius Calculator (Full Pipe)

Full circular pipe hydraulic radius R_h = D/4 (workbook name).

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Physics

Hydrostatic Pressure Calculator

Pressure at depth: P = ρ g h.

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Physics

Ideal Gas Calculator

Ideal gas law (SI). Solve for P, V, n, or T.

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Physics

Impulse and Momentum Calculator

Impulse J = F t = m Δv and resulting final velocity.

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Physics

Index Of Refraction Calculator

Refractive index n = c / v (workbook capitalization).

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Physics

Kinetic Energy Calculator

Translational kinetic energy KE = ½ m v².

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Physics

Knudsen Number Calculator

Knudsen number Kn = λ / L.

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Physics

Length Contraction Calculator

Relativistic length contraction L = L₀ √(1 − v²/c²).

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Physics

Lightning Distance Calculator

Estimate storm distance from thunder delay using the speed of sound.

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Physics

Mach Number Calculator

Mach number M = v / a.

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Physics

Magnitude Of Acceleration Calculator

Absolute value of average acceleration |Δv / Δt|.

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Physics

Malus Law Calculator

Transmitted intensity I = I₀ cos²θ through a polarizer.

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Physics

Moment Of Inertia Calculator

Solid cylinder/disk about central axis: I = ½ m r² (workbook capitalization).

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Physics

Newton's Second Law Calculator

Compute force from mass and acceleration (F = ma).

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Physics

Normal Force Calculator

Normal force on a mass on an incline: N = mg cosθ.

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Physics

Ohm's Law Calculator

Solve for voltage, current, or resistance with Ohm's law.

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Physics

Period Pendulum Calculator

Small-angle simple pendulum period T = 2π √(L/g).

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Physics

Poisson's Ratio Calculator

Poisson's ratio ν = −ε_lateral / ε_axial.

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Physics

Potential Energy Calculator

Gravitational potential energy PE = m g h.

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Physics

Pressure Calculator

Pressure as force over area, P = F / A.

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Physics

Reduced Mass Calculator

Two-body reduced mass μ = m₁ m₂ / (m₁ + m₂).

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Physics

Rotational Kinetic Energy Calculator

Rotational kinetic energy KE = ½ I ω².

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Physics

Series Parallel Resistance Calculator

Equivalent resistance series and parallel for up to 3 resistors.

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Physics

Strain Calculator

Engineering strain ε = ΔL / L₀.

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Physics

Stress Calculator

Engineering stress σ = F / A.

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Physics

Velocity Calculator

Average velocity v = d / t.

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Physics

Work Calculator

Mechanical work W = F d cosθ.

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Sales

Break-Even Units Calculator

Units needed to cover fixed costs.

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Sales

Bundle Discount Calculator

Bundle price after a package discount.

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Sales

Commission Calculator

Sales commission from rate and sales volume.

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Sales

Discount Calculator

Find the sale price and amount saved from a percent discount.

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Sales

Layaway Plan Calculator

Split the remaining balance after a down payment into equal installments.

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Sales

Margin Calculator

Compute gross margin percent from revenue and cost of goods.

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Sales

Markup Margin Converter

Convert markup percent to margin percent and the reverse.

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Sales

Price After Coupon and Tax

Final price after coupon percent and sales tax.

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Sales

Profit Margin Calculator

Compute profit margin from net profit and revenue.

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Sales

Selling Price Calculator

Compute selling price from cost and markup percent.

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Sales

Tip Calculator

Calculate tip amount and total bill from a tip percentage.

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Sales

Total Price Calculator

Multiply unit price by quantity and add sales tax.

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Statistics

Average Calculator

Compute the arithmetic mean of a list of numbers.

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Statistics

Coefficient of Variation Calculator

CV = SD / mean as a percent.

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Statistics

Confidence Interval Calculator

Mean ± z·s/√n confidence interval.

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Statistics

Correlation Calculator

Pearson r from two pasteable data columns.

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Statistics

Linear Regression Calculator

Slope and intercept from two pasteable data columns.

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Statistics

Mean Median Mode Calculator

Find the mean, median, and mode of a data set.

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Statistics

P-value Calculator

Two-tailed p-value for a one-sample z-test with known σ.

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Statistics

Percentile Rank Calculator

Percentile rank from counts below/at a score.

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Statistics

Sample Size Calculator

Sample size for a proportion estimate.

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Statistics

Standard Deviation Calculator

Sample or population standard deviation and variance.

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Statistics

Statistics Calculator

Summary stats: count, sum, mean, median, mode, min, max, stdev.

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Statistics

Z-score Calculator

Convert a raw score to a standard (z) score.

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Time

Stopwatch

Start, pause, reset, and record laps with millisecond precision.

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Travel

Currency Tip Split Calculator

Tip and per-person share after service percent.

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Travel

Flight Duration Calculator

Flight hours from distance and average ground speed.

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Travel

Jet Lag Recovery Calculator

Rough recovery days from time zones crossed.

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Travel

Packing Weight Remaining Calculator

Remaining allowance under a weight limit.

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Travel

Road Trip Cost Calculator

Drive time, fuel volume, and fuel cost.

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Units

Unit Converter

Convert length, mass, temperature, area, volume, energy, and more.

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Weather

Dew Point Calculator

Dew point from temperature and humidity (Magnus; °C or °F).

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Weather

Heat Index Calculator

Heat index from air temperature and relative humidity (°C or °F).

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Weather

Hiking ETA Calculator

Rough hike time from distance, pace, and elevation gain.

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Weather

Rain Convert Calculator

Rainfall mm ↔ inches (mode 0=mm→in, 1=in→mm).

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Weather

Wind Chill Calculator

Wind chill from temperature and wind speed (°C/°F, km/h/mph).

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