Measure your wall
Multiply the wall width by its height. If a large window or doorway will not be painted, subtract its measured area. Use square metres for the most straightforward litre calculation.
Convert wall area into litres
Multiply the remaining wall area by the number of coats and divide by the coverage in square metres per litre. Add a modest allowance for waste, edge work and future touch-ups.
Avoid buying too much
Check whether the paint is sold in 1 L, 2.5 L or 5 L tins. Choose enough for the number of coats, but remember that textured walls, rollers and dramatic colour changes can affect actual coverage.
Example: a 4 m-wide feature wall, 2.4 m high
Area = 4 × 2.4 = 9.6 m². For two coats at 12 m²/L, you need 1.6 litres before extra allowance, or approximately 1.8 litres including 10%. A 2.5 L tin could be suitable if sold in that size.
Frequently asked questions
Can I use the main calculator for one wall?
The main calculator measures four walls of a rectangular room, so do not enter one wall’s dimensions as a whole room. Use the one-wall formula on this page.
Does a dark colour need more paint?
Some colour changes require extra coats or a primer. Follow the coverage and preparation guidance for the specific paint.
These calculations are estimates. Always follow the product’s coverage, preparation and application instructions.