Construction
Paint Estimator Calculator
Estimate paint gallons for walls (length as perimeter).
Free to use — no sign-up or login.
Area × coats
ft²
Gallons
Gallons to buy
Amortization schedule
| # | Date | Payment | Principal | Extra | Interest | Balance |
|---|---|---|---|---|---|---|
Gallons equal painted area times coats, divided by coverage. A 50 ft perimeter, 9 ft height, 2 coats, and 350 ft² per gallon is 2.57 gallons. Gallons to buy is 3.
Sheet goods are on the drywall sheets calculator. The round-up is purchasing, not the paint formula.
Exact gallons, then a purchase count
Gallons stay at two decimals. Gallons to buy is that number rounded up to a whole gallon so you can order a can count.
The wall sketch
The side view is a wall with a stripe for each coat, capped so a large coat count stays readable.
Worked example: 50 ft perimeter
Perimeter 50 ft, height 9 ft, 2 coats, coverage 350 ft²/gal. Gallons 2.57. Gallons to buy 3.
\[ G = (50 \times 9 \times 2) / 350 \]
Frequently asked questions
What does the paint estimator measure?
The example is 2.57 gallons, and the buy line is 3.
How many decimal places does paint estimator show?
The example is 2.57 gallons, and the buy line is 3. Lengths, areas, volumes, and money use two decimals. Purchase counts are whole numbers.
Does paint estimator include waste?
The buy line only rounds up. It does not add a separate waste percentage, and it ignores doors and windows.
Can paint estimator mix units?
No. paint estimator expects every input in the unit printed on its label.
Is paint estimator a code or structural check?
No. paint estimator is a quantity estimate. Local rules and site conditions stay outside the formula.
References
Assumptions and limitations
Openings, cuts, and a waste factor are ignored. Gallons to buy is a purchase round-up of the formula result.