Paint Calculator
Work out how much paint a room needs: wall and ceiling areas with doors and windows deducted, litres per coat, and the cans to actually buy. Add as many rooms as you like, each with its own colour, and see a scaled plan with the wall areas marked.
Paint, openings and units
Coverage varies by product and surface: a flat emulsion on new plaster can take half again as much as the same paint on a sealed, previously painted wall, and a strong colour change can need an extra coat. Check the tin, and treat the answer as a shopping estimate rather than a guarantee.
Room 1
- Wall area
- 38.5 m²
- gross 43.2, openings 4.72
- Ceiling area
- 20.0 m²
- not painted
- Per coat
- 3.85 L
- 38.5 m² ÷ 10.00 m²/L
- 2 coats
- 7.69 L
- 2.03 US gal · 8.08 L with overage
Cans to buy, colour by colour
Includes the extra 5% overage. Can counts are rounded up per colour, because paint mixed for one room will not match another.
| Colour | Rooms | Painted area | Paint needed | 500 ml | 1 L | 2.5 L | 5 L | 10 L |
|---|---|---|---|---|---|---|---|---|
| Warm white | Living room | 76.9 m² | 8.08 L2.13 US gal | 17 cans0.42 L spare | 9 cans0.92 L spare | 4 cans1.92 L spare | 2 cans1.92 L spare | 1 can1.92 L spare |
Wall area
38.5 m²
Ceiling area
0.0 m²
Painted area
76.9 m²
Paint to buy
8.08 L
Room plans with wall areas
Every plan is drawn to scale from the dimensions you entered. Wall areas are net of that room's openings and, taken together, match the wall total above.
Openings deducted: 4.72 m² of 43.2 m² gross wall. Amber marks are doors, blue marks are windows; they are drawn to their real width but spread around the walls for legibility.
About this tool
It turns room dimensions into wall and ceiling areas, deducts your doors and windows, divides by the paint's coverage rate for litres per coat, multiplies by the number of coats, adds an overage and rounds up to whole cans per colour. Metric and imperial both work, with 1 imperial gallon = 3.7854 L and 1 m²/L = 40.7458 sq ft/gal. Everything is computed in your browser; nothing is uploaded anywhere.
- 100% free — no account needed
- Runs in your browser
- Nothing is uploaded
Frequently asked questions
Is Paint Calculator really free?
Yes. Paint Calculator is completely free on PureBrowser — every feature, with no account, no trial, and no credit card.
Does Paint Calculator upload my data?
No. Paint Calculator runs entirely inside your browser, so anything you type, paste, or open stays on your own device.
Do I need to sign up or install anything?
Neither. There is no account and nothing to download — open the page and Paint Calculator is ready to use on desktop or mobile.
Does Paint Calculator work offline?
Once the page has loaded, yes. All of the processing happens locally in your browser, so it keeps working without a connection.
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