Paint calculator
Enter the size of the room, its doors and windows and the number of coats to see how much paint to buy.
Paint needed
A door counts as 1.9 m² (20 ft²) and a window as 1.5 m² (15 ft²). Buy a little extra for touch-ups.
How it works
walls = 2 × (length + width) × height − doors − windowspaint = area × coats ÷ coverageWorked example
- 2 × (5 + 4) × 2.6 = 46.8 m²
- − 1.9 − 2 × 1.5 = 41.9 m²
- 41.9 × 2 coats ÷ 11 = 7.6 litres
Frequently asked questions
How far does a litre of paint go?
Most wall paints cover 10–12 m² per litre per coat on smooth, primed walls (about 350–400 ft² per US gallon). Rough or very absorbent surfaces need more: check the tin and change the coverage field.
How many coats do I need?
Two coats for most jobs. One can be enough when repainting in a similar color with a good paint; three may be needed for a big color change or over a dark color.
Does it include the ceiling?
Only if you tick it. The ceiling is the floor area of the room.