Paint Calculator
This paint calculator tells you how many litres of paint you need to cover a wall. Enter the width and height of the wall, choose how many coats you want to apply, and set the coverage of your paint in square metres per litre. The calculator multiplies width by height to get the total area, multiplies that by the number of coats, and divides by the coverage to return the litres required. It is the quickest way to avoid buying too little (and running out mid-job) or too much (and wasting money on leftover tins).
Litres of paint
Total area
Typical paint coverage is 10-12 m²/L per coat, though it varies with the type of paint and the surface. Remember to subtract the area of doors and windows so you do not buy more than you need.
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How it works
The calculation is straightforward. First the wall area is found by multiplying width by height: area = width × height. That area is then multiplied by the number of coats you plan to apply, because each coat needs its own layer of paint. Finally the result is divided by the coverage rate of the paint, expressed in square metres per litre: litres = area × coats ÷ coverage. For example, a wall that is 4 m wide and 2.5 m high has an area of 10 m². With two coats and paint that covers 10 m² per litre, you need 10 × 2 ÷ 10 = 2 litres. Coverage figures are printed on the tin and usually sit between 10 and 12 m² per litre for a single coat.
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Preguntas frecuentes
- How much paint do I need for a wall?
- Multiply the width of the wall by its height to get the area in square metres, multiply that by the number of coats you plan to apply, then divide by the coverage of the paint (usually 10 to 12 m² per litre for one coat). The result is the number of litres you need. This calculator does all of that for you as soon as you enter the figures.
- What coverage should I use?
- Coverage depends on the paint and the surface. Most wall paints cover 10 to 12 m² per litre for a single coat on a smooth, primed surface. Rough, porous or previously unpainted walls soak up more paint and give lower coverage, so use a value nearer 8 to 10 m²/L. The exact figure is printed on the tin.
- How many coats of paint do I need?
- Two coats is the standard for most jobs and gives an even, durable finish. You may get away with one coat when repainting a similar colour, while a big colour change, a bold shade over white, or bare plaster can need three coats. This calculator lets you set the number of coats so the estimate matches your job.
- Should I subtract doors and windows?
- Yes. Doors and windows are not painted with wall paint, so their area should be removed from the total to avoid overbuying. Measure each opening, add up their areas, and subtract that from the wall area before calculating. For a rough estimate you can subtract about 1.5 to 2 m² per standard door and 1.5 m² per window.
- Is it better to buy a little extra paint?
- A small margin is sensible. Coverage figures are optimistic, surfaces vary, and touch-ups later are much easier if you keep some of the original paint. Adding around 10% to the calculated amount, or rounding up to the next tin size, is a safe approach that avoids a second trip to the store mid-project.