Inputs
ft²
Total wall area to paint (doors and windows excluded).
coats
Primer plus top coats, or top coats alone.
ft²/gal
Area one gallon or liter covers per coat. Check the can label.
%
Allowance for cutting in, spills and rough surfaces.
Estimate
—gal
Surface to cover—
Base paint—
Waste allowance—
Paint required—
Buying in
gal
gal
—
How it’s calculated
paint = ( wallArea × coats ) ÷ coverage × ( 1 + waste% ÷ 100 )
- 1. Net surface = wall area × coats
- 2. Base paint = net surface ÷ coverage rate
- 3. Final = base paint × (1 + waste factor)
- 4. Round up to whole cans when you buy