Paint Calculator
How much paint a room needs, and how many tins.
Paint Calculator works out the litres a room needs from its wall area, the doors and windows taken off, the number of coats and the coverage rate printed on the tin, then turns that into whole tins with the leftover shown. Ceilings and woodwork are worked out separately. Nothing you type is uploaded.
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Runs entirely on your device. No file or text you enter here is uploaded. How to verify it.
How to use Paint Calculator
- Enter the room dimensions, or the total wall area, and take off the doors and windows.
- Set the coverage on your tin, the number of coats and what the walls are like now.
- Read the litres, the tin combination and how much is left over.
Questions about Paint Calculator
Why does the first coat on bare plaster cover so much less?
Fresh plaster is porous, so the first coat is partly absorbed into the wall rather than deposited on it. The trade answer is a mist coat: emulsion thinned with 10 to 20 per cent water so it soaks in and grips, which typically covers around half the area the tin claims. Painting neat emulsion straight onto new plaster leaves a film that can peel off in sheets a year later, so the reduced first coat here is deliberate, not pessimism.
How many coats do I actually need?
Two is the normal answer over a sound, similarly coloured wall. Going from a dark colour to a light one usually takes three, and the coats have to be thin: opacity comes from repeated layers, and a coat laid on heavily runs, sags and takes days to harden. The tool lets you set the number and shows what each extra coat costs in litres.
Why are the coverage figures different in metric and imperial?
Because the two markets measure the same thing under different assumptions. A European tin states a spreading rate on a smooth, sealed surface and typically quotes 11 to 14 square metres per litre; a North American tin quotes a more conservative full-hide figure, usually 350 to 400 square feet per gallon. Converting one into the other looks wrong to whoever reads it, so each unit system has its own presets.
Does it handle the ceiling and the skirting boards?
Yes, both separately, with their own coverage rate and coat count. The ceiling is the floor area. The woodwork figure is the distance round the room, less the door openings, multiplied by the height of the skirting, plus an allowance for door frames and window sills — trim paint spreads further than emulsion and comes in smaller tins, so it is never rolled into the wall total.
Is anything I enter sent anywhere?
No. The arithmetic runs in JavaScript inside your own tab. Your last settings are kept in your browser's local storage so the page remembers the room when you come back, and that copy stays on your device — there is no account, no upload and no server that ever sees the figures.
Is Paint Calculator really free, with no limits?
Yes. There is no account, no daily cap, no file-size tier and no watermark, because there is no server cost to recover. The site is funded by clearly disclosed partner recommendations on the Partners page, never by metering the tools.
Are my files or text uploaded when I use Paint Calculator?
No. Everything is processed by JavaScript running in your browser, on your device. You can verify it: open your browser's developer tools, switch to the Network tab, and use the tool. You will see no request carrying your data — because there is nowhere for it to go.