Paint Calculator
Work out how much paint a room needs: the paintable wall area after doors and windows, the litres or gallons across your coats, and the whole cans to buy.
This free paint calculator works out how much paint a room needs: the paintable wall area after doors and windows, the litres or gallons across your coats, and the whole cans to buy. It answers how much paint for a room and how many coats, using the coverage printed on your tin. Runs in your browser, no sign-up.
Read the guide: How Much Paint Do I Need for a Room?Room
Paint to buy
1 can
0.71 gal · 2 coats
- Paintable area
- 124 ft²
- Area with coats
- 248 ft²
- Paint (gal)
- 0.71
- Cans (1 gal)
- 1
Covering 124 ft² with 2 coats at 350 ft²/gal. Buy whole cans and keep the leftover for touch-ups.
Coverage varies by paint and surface. Bare, porous or dark walls drink the first coat, so lean to the higher can count. Check the figure printed on the tin.
How it works
- 1
Measure the walls
Enter one wall as length by height, or a whole room as floor length, width and ceiling height. Feet or metres.
- 2
Deduct openings
Add the number of doors and windows and set your coats. Standard door and window areas come off the total.
- 3
Get the cans
See the paintable area, the litres or gallons needed, and the whole cans to buy, with primer if you want it.
Instant & 100% private — nothing is uploaded
Every calculation runs locally in your browser. The income, balances and goals you enter stay on your own device and are never sent to a server — nothing is stored, logged or shared.
Frequently asked questions
- How much paint do I need for a room?
- Add up the wall area, subtract the doors and windows, multiply by the number of coats, then divide by the paint’s coverage. The calculator does this and rounds up to whole cans.
- How much area does one can cover?
- A litre of wall paint covers about 10 m², and a US gallon about 350 sq ft, for one coat on a smooth sealed surface. Both figures are editable, so use the number printed on your tin.
- How many coats of paint should I use?
- Two coats is standard for even colour and coverage. A like-for-like refresh can take one; a big colour change or bare wall may want a primer coat first.
- Do I subtract doors and windows?
- Yes. The calculator takes off a standard door and window area for each one you enter, so you are not buying paint for surfaces you will not cover.
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