Skip to content
Everyday maths / Free tool

Paint quantity calculator

Estimate litres of paint from wall area, openings, coats and stated coverage.

Your numbersLive result
Choose the question you want to answer.
Required. Greater than 0. Use up to 6 decimal places, without commas or currency symbols.
Required. Greater than 0. Use up to 6 decimal places, without commas or currency symbols.
Required. 0 or more. Use up to 6 decimal places, without commas or currency symbols.
Required. Greater than 0. Whole numbers only. Maximum 20. Whole number from 1 to 20.
Required. Greater than 0. Use up to 6 decimal places, without commas or currency symbols.
Required. 0 or more. Maximum 100. Use up to 6 decimal places, without commas or currency symbols.

Example values are prefilled. Change any number to calculate.

Estimated paint needed

9.68 litres

Paintable area
44 m²
Area across all coats
88 m²

Assumes walls share the entered height. Subtract openings once, multiply by coats and divide by your paint’s stated coverage, then add the allowance. Check the result against available tin sizes; this tool does not round to a tin size.

Your inputs stay in this browser.

The working behind the answer

How to use this calculator

Add together the lengths of the walls you want to paint. Enter their common height and the combined area of openings. Coverage should come from the paint you intend to use. The allowance lets you account for some extra usage without inventing a universal wastage rate.

The formula

Estimate wall paint

Litres = (wall length × height − openings) × coats ÷ coverage × (1 + allowance ÷ 100)

A worked example

Walls totalling 20m long and 2.4m high have an area of 48m². Subtract 4m² of openings: 44m². Two coats at 10m² per litre need 8.8 litres, or 9.68 litres with a 10% allowance.

Good to know

For walls of different heights, calculate them in separate batches or use an equivalent total area. Ceilings are not automatically included. The result is litres, not a number of tins; porous surfaces and paint types can affect coverage.

Common questions

Are doors and windows subtracted for each coat?

Their area is subtracted from the wall area once, then the remaining area is multiplied by coats.

Does it round up to a paint tin?

No. Compare the required litres with the tin sizes available for your chosen paint.