Paint Calculator
Litres of paint needed.
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About Paint Calculator
The Paint Calculator estimates how much paint you need for a project. Enter your total wall area, or a wall's length and height to work it out automatically, then set the number of coats and your paint's coverage per litre. It subtracts about 1.8 m² for each door or window and tells you how many litres to buy.
It's completely free with no sign-up. Everything runs entirely in your browser — nothing you type is uploaded or stored on a server, so your measurements stay private on your own device.
Frequently asked questions
- How does the paint calculator work out how much paint I need?
- It uses paintable area × number of coats ÷ coverage per litre. Paintable area is your total wall area minus roughly 1.8 m² for each door or window you enter. The result is rounded up to whole litres so you know how much to buy.
- What coverage per litre should I use?
- Most emulsion and wall paints cover about 6–12 m² per litre depending on the paint, surface, and colour. The default is 10 m²/L, but check your tin's label and enter that figure for the most accurate estimate. Porous or textured surfaces use more paint.
- Why does it round the litres up?
- Paint is sold in fixed tin sizes, and running out mid-coat leaves visible joins. The main result rounds up to the nearest whole litre so you buy enough to finish the job, while the stat grid also shows the exact litres needed for reference.
- Is this paint calculator free to use?
- Yes, it's completely free with no account, sign-up, or limits. Use it as many times as you like.
- Is my data uploaded or stored anywhere?
- No. The calculator runs entirely in your browser using JavaScript. Your measurements are never sent to a server, saved, or shared — everything stays on your device.
- Can I calculate paint for a whole room?
- Yes. Add up the area of all the walls you want to paint and enter it as the total wall area, or measure the combined length and use your ceiling height. Then enter the total number of doors and windows across those walls to subtract them.