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Paint Calculator
Guessing how many tins to buy is how you end up back at the shop mid-job — or with three spare 5-litre tins in the shed. Punch in the room or the wall area, pick your coats, and get an honest litres figure with the tins to match.
Suggested tins: —
Every figure here is an estimate. Coverage varies with surface, colour change and how you apply it — always round up and keep a little in reserve for touch-ups.
How much paint do I need per m²?
As a rule of thumb, one litre of interior emulsion covers roughly 10–14 m² in a single coat, so most walls take about one litre for every 12 m² per coat. Divide your total wall area by the coverage figure on the tin, then multiply by the number of coats. This calculator does exactly that and rounds up so you're never caught short.
How many coats of paint do I need?
Two coats is standard for most emulsion jobs and gives an even, durable finish. You may get away with one coat when repainting a similar colour over a sound, previously-painted surface — but bare plaster, big colour changes (especially dark to light) and patchy walls will usually want two coats plus a mist or primer coat first. When in doubt, budget for two.
Does this include the ceiling?
No — the room-dimensions mode works out wall area only, using 2 × (length + width) × height. If you're painting the ceiling too, add its area (length × width) to your total. The easiest way is to switch to "Total wall area" mode and enter the combined walls-plus-ceiling figure, or run the calculator twice and add the litres together. Ceilings often need a bit more paint per m² because they're less forgiving to roller marks.
Painting a freshly plastered or boarded wall?
New plasterboard or a fresh skim coat needs a mist coat (watered-down first coat) before it behaves like a normal painted wall — that's part of why bare plaster is listed above as a job that usually wants two coats plus a primer. If you haven't boarded the wall yet, our Plasterboard Calculator works out the sheets, screws and jointing compound first. Papering instead of painting? Our Wallpaper Calculator works out rolls by the drop method.
Does this tool store my details?
No. There's no sign-up and nothing to submit — every calculation runs entirely in your browser as you type. Nothing you enter is uploaded, saved or sent anywhere, so you can use it as many times as you like without leaving a trace.
Please note: this tool gives a guide or estimate only. It may not be 100% accurate and is not professional advice — always check the figures before you rely on them. Nothing you enter is uploaded — the calculation runs entirely in your browser.
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