Paint Calculator

Estimate how much paint you need for a room from the wall length, height, doors, windows and coats.

How much paint do I need for a room?

Paint = (wall length × height − doors − windows) × coats ÷ coverage. A room with 16 m of walls, 2.5 m high, one door and two windows has about 35 m² to paint; two coats at 10 m² per litre need about 7 litres.

Coverage

Most emulsion covers 10–12 m² per litre (350–400 ft² per US gallon) per coat on smooth walls. Rough, porous or new plaster needs more — or a primer first. Buy about 10% extra for touch-ups.

Frequently asked questions

How many coats do I need?

Two coats for most colour changes; one may do when repainting the same colour.

Does it include the ceiling?

No — add the ceiling area (length × width) separately.

What door and window sizes are used?

1.9 m² (20 ft²) per door and 1.5 m² (16 ft²) per window.