Exterior House Paint Calculator
Calculate exterior wall area and gallons of paint needed using home dimensions, wall height, stories, coverage per gallon, coats, and waste. Includes a 15% deduction option for windows and doors.
Inputs
Exclude windows/doors (15% deduction)
Tip: Increase waste for textured siding or difficult access and disable the deduction if you need a conservative estimate.
Results
Exterior wall area
1,260 sq ft
Perimeter: 140 ft
Adjusted paintable area
2,356.2 sq ft
Includes coats, waste, and an optional 15% openings deduction.
Gallons needed
6.73
Assumptions
- Exterior wall area is based on a rectangular footprint and ignores attached garages or porches.
- The 15% deduction is a simplified allowance for windows and doors.
- Coverage per gallon is for one coat on a smooth surface; adjust for texture or porous siding.
Example
A 40 ft by 30 ft home with 1 story(ies) at 9 ft wall height needs about 6.73 gallons when coverage is 350 sq ft per gallon, with 2 coats and 10% waste.