Paint Coverage Calculator — How Much Does a Tin Cover?
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How much does 5 litres of paint cover? On a smooth, previously painted wall, roughly 60 square metres with one coat — or about 30 square metres if you are doing the usual two. This calculator works it out for any tin size, and adjusts for the surface you are actually painting, because bare plaster and textured walls drink far more than the tin implies.
Know your room size and want the litres instead? Use the paint quantity calculator.
Note: Manufacturer coverage figures assume ideal conditions — a smooth, sealed, mid-tone surface. Real-world coverage is usually lower. Add about 10% for touch-ups.
How this calculator works
The calculator multiplies your tin size by the coverage the manufacturer states per litre, which gives the theoretical area for a single coat. It then scales that down by a factor for your surface type, because porous or textured surfaces absorb more paint per square metre than the smooth test wall the manufacturer used. Finally it divides by the number of coats, since two coats over the same wall consumes twice the paint. The headline result is the area one tin will genuinely cover at your chosen number of coats.
Worked example
A standard 5-litre tin stating 12 m² per litre covers 60 m² in theory with one coat. On a smooth, previously painted wall at two coats, that is 30 m² — enough for a typical small bedroom. On bare plaster, the 60% factor drops effective coverage to 7.2 m² per litre, so the same tin covers only 36 m² in one coat, or 18 m² in two. That difference is why bare plaster jobs so often run short.
Frequently asked questions
How much does 5 litres of paint cover?
About 60 square metres with one coat on a smooth, previously painted wall, assuming a typical 12 m² per litre. With the standard two coats, that becomes roughly 30 square metres — enough for a small bedroom. On bare plaster expect closer to 18 square metres at two coats.
How much does 2.5 litres of paint cover?
Around 30 square metres at one coat, or 15 square metres at two, on a smooth surface. A 2.5-litre tin typically does one small room's walls with two coats only if the room is very compact — for most bedrooms you want 5 litres.
How much does 10 litres of paint cover?
Roughly 120 square metres at one coat, or 60 square metres at two, on smooth previously painted walls. That covers the walls of a large living room or two average bedrooms.
Why does my paint cover less than the tin says?
Stated coverage is measured on a smooth, sealed, uniformly coloured test surface under ideal conditions. Textured, porous or unpainted walls absorb considerably more, and covering a dark colour with a light one needs extra coats. Use the surface type selector above for a realistic figure.
Does primer change how much topcoat I need?
Yes, and it usually saves money. Priming bare plaster seals the surface so your topcoat behaves like it would on a previously painted wall — closer to the full stated coverage rather than the 60% figure. On large bare-plaster jobs, primer often costs less than the extra topcoat it saves.
Should I buy extra paint?
Add about 10% beyond your calculated figure. It covers touch-ups and mistakes, and it avoids the real risk of a second tin from a different batch showing a subtle colour shift on the wall.