How to calculate how much paint you need
Paint math is simple: find the paintable area, multiply by the number of coats, then divide by how much a gallon covers (about 350 sq ft).
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- Wall area = 2 x (length + width) x height.
- Subtract about 21 sq ft per door and 15 sq ft per window.
- Paint needed (gallons) = area x coats / 350. Round up to whole cans.
Frequently asked questions
- How do you calculate paint for a room?
- Multiply the perimeter by the wall height, subtract doors and windows, multiply by coats, then divide by 350.
- How much does a gallon of paint cover?
- About 350 sq ft per coat on smooth, primed walls — less on rough or porous surfaces.