Paint Coverage by Coats Calculator

About this calculator

Paint quantity scales directly with both the number of coats and the paint's spread rate — the area one litre covers, usually printed on the tin, typically 10–12 m² per litre per coat for emulsion on a reasonably smooth wall. The formula is straightforward: litres needed = (wall area × number of coats) ÷ spread rate, but it is easy to underestimate because two coats do not just mean "twice as thorough," they mean literally double the litres.

DIY decorators and painting contractors run this before buying paint because tins are sold in fixed sizes (1L, 2.5L, 5L, 10L) and buying short means a mismatched batch on a return trip, while overbuying wastes money on paint that may not colour-match a future top-up — getting the coat count and spread rate right up front avoids both problems.

This calculator takes your wall area, number of coats and the paint's spread rate and returns exactly how many litres to buy, so you can pick the right tin sizes in one trip.