How much paint do you need?

Work out the wall area (perimeter × height, minus doors and windows), multiply by the number of coats and divide by the paint's spreading rate — usually 10–14 m² per litre for emulsion on smooth, sealed walls. A medium bedroom's walls typically need 5–7 litres for two coats.

Two coats over a sound wall of a similar colour. New plaster needs a thinned mist coat first; a big colour change often needs a third coat.

More than you would think: bare plaster is porous, so allow a mist coat (emulsion thinned with water) on top of the two finish coats. The calculator adds it when you choose new plaster.

Yes — around 10% extra covers touch-ups and absorbent patches, and keeping some from the same batch makes future repairs match. The calculator includes that margin.

Often, for the walls of a small to medium room. At around 12 m² per litre, 5 litres covers roughly 60 m² of wall in one pass, which is two coats on about 30 m² — a 3.5 m × 3 m bedroom with standard ceilings. A larger room, a tall period room or a strong colour change needs more, and the ceiling is extra.

Usually not for two coats. 2.5 litres covers about 30 m² in a single coat, so it suits one feature wall with two coats, a box room's walls with one coat, or a ceiling of around 12 m² with two coats. Enter your room above to check.