Room paint calculator
Estimate wall paint from room dimensions, opening area, coats and the coverage printed on your paint tin.
How the estimate works
Wall area = 2 × (room length + room width) × height, minus openings. Paint volume = net wall area × coats ÷ coverage. Divide by container size and round up.
Worked example
A 12 × 10 ft room with 8 ft walls and 40 square feet of openings has 312 square feet to paint. Two coats at 350 square feet per US gallon need about 1.78 US gallons, or two 1-gallon containers.
Before you order
- This estimates the four walls of a rectangular room. Ceiling, trim and primer are not included.
- Use the manufacturer’s coverage for the surface and application method. Porosity and application losses can affect the final amount.
- In imperial mode, liquid units are US gallons. Metric mode uses litres. Changing currency only changes the price format.
Common questions
Can I include a ceiling?
This version calculates walls only. Estimate a ceiling separately from its area and the paint’s coverage.
Does it account for different colours?
No. Run separate estimates for the areas painted in each colour.
