How much paint do I need for a 12x12 room?
A 12 x 12 ft room with 8 ft ceilings, one door and two windows has about 338 sq ft of wall to paint. At the usual coverage of about 407 sq ft per gallon that is 1.66 gallons for two coats, so you buy 2 gallon cans. Taller ceilings, a single coat and the metric version are in the tables.
Paint for a 12 x 12 ft room
Wall area is the perimeter times the ceiling height: (12 + 12) x 2 = 48 ft of wall, times the height. The tables deduct one door (about 3 x 7 ft) and two windows (about 3 x 4 ft each). Change these in the paint calculator if your room is different.
| Ceiling | Wall area (sq ft) | 1 coat (gal) | Cans (1 gal) | 2 coats (gal) | Cans (1 gal) |
|---|---|---|---|---|---|
| 8 ft | 338 | 0.83 | 1 | 1.66 | 2 |
| 9 ft | 386 | 0.95 | 1 | 1.89 | 2 |
| 10 ft | 434 | 1.06 | 2 | 2.13 | 3 |
Reading the table
- Cans are rounded up to whole gallons. If the exact figure is just over a whole number, a quart may be enough for the difference, but keep some for touch-ups from the same batch.
- Trim, doors and radiators are painted with a different product and are not included. A door and its frame take roughly a quart per coat.
- Primer is separate. New drywall, bare plaster and patched areas need it before the colour coats.
Metric: a 4 x 4 m room
The same room in metres is 4 x 4 m. Coverage of 10 m² per litre per coat is a common label figure for emulsion; check your can.
| Ceiling height | Wall area (m²) | Litres (2 coats) | 5 L cans | 2.5 L cans |
|---|---|---|---|---|
| 2.4 m | 34.1 | 6.8 | 2 | 3 |
| 2.7 m | 38.9 | 7.8 | 2 | 4 |
Why coverage on the can is the number that matters
Two paints in the same aisle can differ by 30% in coverage, and a rough or unsealed wall soaks up much more than a smooth one. The estimate is only as good as the coverage you put in, so read the can (it is usually given per coat) and, on porous surfaces, use the lower end of the range the manufacturer prints.
Frequently asked questions
- How much paint for a 12x12 room with 8 ft ceilings?
- About 1.66 gallons for two coats on the walls (2 gallon cans), after deducting one door and two windows. One coat is 0.83 gallons.
- Do I need two coats?
- Usually yes. One coat is enough only when repainting the same colour on a sound surface. Changing colour, covering a dark wall or painting fresh plaster needs two coats, and a primer or mist coat on bare plaster on top of that.
- Does this include the ceiling?
- No, the tables are walls only. The 12 x 12 ft ceiling is 144 sq ft and takes about 0.71 gallons for two coats, so one gallon can of ceiling paint.
- How many square feet does a gallon of paint cover?
- Most cans quote 350 to 400 sq ft per gallon per coat on a smooth, sealed surface; this page uses 407. Textured or porous walls take more, so use the figure on your can in the calculator.
Last updated 2026-09-11. Figures are planning estimates from typical product data: check the yield, size or coverage printed on what you buy and round up.