Paint Coverage Calculator
How it works
Doors and windows come out of the wall area first, since paint does not go on them. What is left gets multiplied by the number of coats — two coats means covering that same area twice — and the total is divided by how far one gallon of your specific paint spreads, to get the gallons needed.
Frequently asked questions
Why does coverage per gallon vary between products?
Coverage is a property of the specific paint — its thickness, finish, and how far a manufacturer expects it to spread — not a fixed physical rule. This tool's 350 sq ft default is a common ballpark for a wall paint in normal conditions, but the can in front of you is the number that actually applies.
Why does this default to two coats?
Most paints need two coats for even, opaque coverage, especially over a different existing wall color where one coat can leave the old color showing through in patches. A single coat is enough for a same-color touch-up, which is why coats is a field you can change rather than a fixed assumption.
How accurate is subtracting doors and windows?
It's an approximation — it just removes a flat area from the total. For a more precise number, measure each door and window opening and add up their areas yourself, rather than estimating one lump figure for all of them.