Paint calculator

How it is calculated

Doors and windows are subtracted from the total wall area. What is left is multiplied by the number of coats and divided by the coverage: the area one liter, or one US gallon, covers in a single coat.

Paint = (wall area − doors − windows) × coats ÷ coverage

Example

A 12 × 14 ft bedroom with 8 ft walls has 2 × (12 + 14) = 52 ft of wall, so 416 ft². Taking out one 3 × 6.67 ft door (20.01 ft²) and two 4 × 4 ft windows (32 ft²) leaves 363.99 ft². Two coats at 400 ft²/gal need 1.82 gal, shown as 1.9 gal.

In metric, a 4 × 3 m room with 2.5 m walls has 14 m of wall, so 35 m². Without a 0.8 × 2.1 m door that is 33.32 m², and two coats at 10 m²/L need 6.7 L.

Limitations

If you enter wall dimensions instead, the area is the total wall length times the height. The result is rounded up to the nearest 0.1 L or 0.1 gal. Rough surfaces, new plaster or a strong color change can take more paint: in those cases use the lowest coverage the manufacturer gives. Primer is not included.