Material calculator
Paint Calculator
Estimate how much paint you need from wall dimensions, doors and windows, number of coats, and coverage per gallon.
How to use this calculator
Enter room length, room width, and wall height. Subtract the combined area of doors and windows, then enter the number of coats and the coverage printed on the paint label.
Enter an optional price per can to estimate material cost.
How the estimate is calculated
Wall area is 2 × (room length + room width) × wall height. Door and window area is subtracted before multiplying by the number of coats. The selected waste percentage is then added to the coated area. The result is divided by coverage per gallon, and full cans are rounded up before cost is calculated.
Example
A 12 ft × 10 ft room with 8 ft walls has 352 sq ft of wall area. After subtracting 40 sq ft for doors and windows, two coats cover 624 sq ft. At 400 sq ft per gallon, the estimate is 1.56 gal, or two 1-gallon cans.
Before you buy
Coverage changes with surface texture, color change, application method, and the specific paint. Use the product label rather than assuming the example coverage applies.
Frequently asked questions
Are ceilings included?
No. This calculator estimates walls only; ceilings are not included.
Why are doors and windows subtracted before coats?
Their area is not painted on any coat, so the deduction belongs before the remaining wall area is multiplied.
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