How to use
- Choose Imperial or Metric.
- Enter the room length, width and wall height.
- Enter the number of doors, windows and coats, and the coverage from your paint can.
- Read how much paint you need.
Options explained
- Coverage
- How much wall one gallon or litre covers per coat — usually 350–400 ft² per gallon, or about 10 m² per litre. It is printed on the can.
- Coats
- Two coats is standard; a big colour change or new drywall may need a primer coat too.
- Doors and windows
- Each door subtracts about 21.5 ft² (2 m²) and each window about 16 ft² (1.5 m²).
How much paint for common rooms
Walls only, 8 ft ceilings, one door and two windows, two coats at 350 ft² per gallon:
| Room | Wall area | Area to paint | Paint for two coats |
|---|---|---|---|
| 10 × 10 ft | 320 ft² | 266 ft² | 1.5 gallons |
| 12 × 10 ft | 352 ft² | 298 ft² | 1.7 gallons |
| 12 × 12 ft | 384 ft² | 330 ft² | 1.9 gallons |
| 14 × 12 ft | 416 ft² | 362 ft² | 2.1 gallons |
| 16 × 14 ft | 480 ft² | 426 ft² | 2.4 gallons |
In metric, with 2.6 m walls, one door and one window, two coats at 10 m² per litre:
| Room | Wall area | Area to paint | Paint for two coats |
|---|---|---|---|
| 3 × 3 m | 31.2 m² | 27.7 m² | 5.5 L |
| 4 × 3 m | 36.4 m² | 32.9 m² | 6.6 L |
| 5 × 4 m | 46.8 m² | 43.3 m² | 8.7 L |
Round up to whole cans: for the 12 × 12 ft room that means two 1-gallon cans, not one gallon and a quart.
Frequently asked questions
How much paint for a 12 × 10 room?
With 8 ft walls, the walls are 2 × (12 + 10) × 8 = 352 ft². Minus one door and two windows that is about 298 ft²; two coats at 350 ft² per gallon need about 1.7 gallons.
Does this include the ceiling?
No, only the walls. Work out the ceiling separately as length × width.
Should I round up?
Yes. Buy whole cans and keep a little left over for touch-ups.
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