Paint calculator
Work out how much paint you need for a room or a wall. Enter the total wall length, the height, how many coats you are doing and how many doors and windows to leave out, and this calculator gives you the litres and the tins to buy.
Paint calculator
Enter your measurements in metres. Everything updates as you type, and nothing is sent anywhere.
Based on a coverage of about 12 square metres per litre per coat, which suits most matt and silk emulsion. Heavily textured walls, bare plaster and strong colour changes cover less, so round up. Each door or window is taken as about 1.8 square metres. Ceilings are not included, so add a ceiling as its own wall length by width sum if you need it.
Common questions
How much paint do I need?
Work out the wall area (length times height), take off about 1.8 square metres for each door and window, then multiply by the number of coats and divide by the coverage, about 12 square metres per litre. The calculator does it for you and turns the litres into 5-litre and 2.5-litre tins.
How many coats of paint do I need?
Two coats is normal for a good finish over an existing similar colour. Allow three if you are going from dark to light, painting bare plaster (which usually wants a watered-down mist coat first), or using a strong or patchy colour. Set the coats in the calculator to match.
How much does a litre of paint cover?
About 12 square metres per litre per coat for standard emulsion on a sound, previously painted wall. Bare plaster, textured surfaces and deep colours cover less, sometimes only 8 to 10 square metres, so treat the figure as a guide and round tins up.
These are independent guide prices based on typical UK jobs in 2026. Your actual cost depends on your property, spec, access and where you live. Always get at least three written quotes before committing. These quantities are a guide to help you order. Always round up and check with your supplier before buying.