Formula
Paintable area = perimeter x wall height - openings. Total paint area = paintable area x coats x waste factor. Gallons = total area / coverage.
Wall paint estimator
Paint Calculator
Estimate how much paint you need for a room or wall project. Enter room perimeter, wall height, number of coats, paint coverage, and openings to calculate gallons and liters.
Calculate paint needed
Paintable area
0
Gallons needed
0
Liters needed
0
1-gallon cans
0
Example
A room with 60 ft perimeter and 8 ft walls has 480 sq ft wall area before subtracting doors and windows.
Useful for
Bedrooms, living rooms, offices, rental refreshes, accent walls, repainting estimates, and supply planning.
Paint estimating notes
Coverage varies by paint type, surface texture, primer, color change, roller method, and wall condition. Dark color changes or porous surfaces may need extra coats.
FAQ
Should ceiling paint be included?
This calculator focuses on walls. Add ceiling square footage manually to the opening-adjusted wall area if you are painting ceilings too.
How much does one gallon cover?
Many interior paints cover about 300 to 400 square feet per coat, but the exact value depends on the paint and surface.