How this calculation works
Measure only the area you intend to paint. Coverage should come from the selected product for the actual surface. The allowance can account for losses and application conditions.
Litres = area × coats ÷ coverage × (1 + allowance/100)A worked example
100 m² at 10 m²/L for 2 coats needs 20 L, or 22 L with 10% allowance.
Good to know
Coverage varies by surface, preparation, product and application. Container-size rounding and primer are not included.
Coats multiply coverage, not wall area
A 100 m² wall receiving two coats needs the equivalent of 200 m² of one-coat coverage. If the product covers 10 m² per litre per coat, that gives 20 litres before allowances. The physical wall area has not changed; the application work has.
Coverage can be a more important uncertainty than the wall measurement. If actual coverage is lower than the entered figure, the required volume rises in inverse proportion.
Use the right surface and the right product coverage
Measure the areas to be painted and decide how openings, trim and ceilings are treated. A room’s floor area is not automatically its wall area. Keep primer or a different finish in a separate calculation if its coverage differs.
The tool returns litres, not a shopping basket of containers. Round to the available pack sizes after checking application conditions, product instructions and the desired spare quantity.
A few questions, answered
Is the coverage figure for one coat?
Yes. Enter the product’s area per litre for one coat, then set the number of coats.
Does it round to paint-can sizes?
No. It returns a volume estimate; available container sizes need a separate ordering decision.