Paint Quantity Calculator
Buying too little paint means a second trip and a possible colour-batch mismatch; too much wastes money. Enter your wall dimensions and how many coats you plan, and this estimates the litres required.
Note: Add ~10% for touch-ups, and subtract large windows or doors from your wall length for a tighter estimate.
How this calculator works
The calculator multiplies your total wall length by the wall height to get the wall area in square metres, multiplies that by the number of coats, and divides by how many square metres a litre of your paint covers. Coverage is printed on the tin and is usually between 10 and 13 square metres per litre, though porous or dark-over-light surfaces drink more.
Worked example
For 20 metres of wall at 2.4 metres high, that is 48 square metres per coat. Two coats make 96 square metres. At 11 square metres per litre, you need about 8.7 litres — so you would buy three 3-litre tins, leaving a little spare for touch-ups.
Frequently asked questions
Should I subtract windows and doors?
For a tighter estimate, yes — reduce your wall length to account for large openings. For a quick estimate, leaving them in simply builds in a small safety margin.
How many coats do I need?
Two coats is standard for an even finish. You may need three when painting a light colour over a dark one, or when covering bare plaster.
Why does my paint cover less than the tin claims?
Stated coverage assumes a smooth, sealed surface. Textured, porous, or previously unpainted walls absorb more, so round up when in doubt.