Units
Unit Converter
Convert length, mass, temperature, area, volume, energy, and more.
Free to use — no sign-up or login.
This unit converter keeps several measurement families in one place: pick a family, enter a value, and read the same quantity in the other units of that family. Length, mass, and most other groups scale through a shared base unit. Temperature is different — Celsius, Fahrenheit, and Kelvin need slope and offset, not a single multiply.
If you only ever convert one dimension, a focused page can be quicker: try the Length Converter, Weight Converter, or Temperature Converter. The method tutorial is How to Convert Units. Currency, time zones, and shoe sizes are not unit families here.
How proportional families convert
For length, mass, area, volume, and similar families, each unit has a factor to a shared base (for length, the meter). The converter multiplies your value by the from-unit factor, then divides by the to-unit factor. Exact definitions such as 1 in = 2.54 cm and 1 ft = 0.3048 m are the usual SI-linked constants; displayed results may round for readability.
Temperature uses offset, not one factor
You cannot convert Celsius to Fahrenheit by multiplying by a single length-style constant. The page uses the linear maps in How it works: °F = °C × 9/5 + 32, and K = °C + 273.15. Absolute zero and boiling/freezing checkpoints are the usual sanity checks, not a weather forecast.
Length: 12 inches to centimeters
By definition, 1 inch = 2.54 cm, so 12 in = 12 × 2.54 = 30.48 cm (exactly one foot). In the length family that is the same as converting 12 in → meters (0.3048 m) → centimeters.
\[ 12\,\mathrm{in}=12\times 2.54=30.48\,\mathrm{cm} \]
Temperature: 0 °C to Fahrenheit and Kelvin
Freezing water on the Celsius scale: °F = 0 × 9/5 + 32 = 32 °F, and K = 0 + 273.15 = 273.15 K. Those matches are offset formulas, not the proportional length path.
\[ 0^{\circ}\mathrm{C}=32^{\circ}\mathrm{F}=273.15\,\mathrm{K} \]
Frequently asked questions
Why is temperature different from length?
Length and mass conversions are proportional. Celsius, Fahrenheit, and Kelvin differ by slope and offset, so you cannot multiply by one constant the way you convert meters to feet.
When should I use this page instead of a single-family converter?
Use this hub when you switch families often or want one bookmark. Use a dedicated length, weight, or temperature converter when you want a page aimed at that dimension alone — the factors are the same class of conversion.
Are the factors exact?
Many SI ties are exact by definition (for example the inch–meter link). The UI may round the number you see. For lab or legal work, confirm the constant and significant figures your context requires.
Can I convert currency or time zones here?
No. Those are not physical unit families in this tool. Stick to the listed measurement groups; money and civil time need other data.
Sources
Assumptions and limitations
Conversions apply within the selected family using the factors and temperature maps on this page. Results may be rounded for display. This is not a currency, timezone, or clothing-size converter.