How Much Paint Do I Need? (Coverage & Room Sizes)
Part of Interior & Finishes
Quick answer
Gallons needed = (wall area × number of coats) ÷ 350. One gallon covers about 350 ft² per coat on smooth, primed walls. A typical 12×12 ft bedroom needs about 2 gallons for two coats, and most average rooms need 1–2 gallons.
Paint is estimated by coverage: a gallon covers roughly 350 square feet in one coat. So the math is wall area × coats ÷ 350, rounded up. The only adjustments are surface texture and big color changes, which lower coverage.
Coverage per container
| Container | Covers (1 coat) | Good for |
|---|---|---|
| 1 quart | ~90 ft² | Trim, doors, touch-ups |
| 1 gallon | ~350 ft² | A small room, one coat |
| 2 gallons | ~700 ft² | An average room, two coats |
| 5 gallons | ~1,750 ft² | Whole-house or large jobs |
Gallons by room size (walls, 2 coats, 8 ft ceiling)
| Room | Wall area | Paint (2 coats) |
|---|---|---|
| 10 × 10 ft | ~320 ft² | ~2 gal |
| 12 × 12 ft | ~384 ft² | ~2 gal |
| 12 × 16 ft | ~448 ft² | ~2–3 gal |
| Living room 14 × 20 ft | ~544 ft² | ~3 gal |
The steps
- Wall area = room perimeter × ceiling height. (For a 12×12 room: 48 ft × 8 ft = 384 ft².)
- Subtract roughly 20 ft² per door and 15 ft² per average window if you have large openings.
- Multiply by the number of coats (usually 2).
- Divide by 350 and round up. Add a quart for touch-ups.
Enter your wall area and coats in the paint calculator and it returns the exact and rounded-up gallons, plus how much will be left over in the cans.
FAQs
How many square feet does a gallon of paint cover?
About 350 square feet in one coat on smooth, primed drywall. Rough, porous or previously unpainted surfaces drop that to 250–300 ft², and a dark-to-light color change can need an extra coat.
How much paint do I need for a bedroom?
Most bedrooms need about 2 gallons for two coats on the walls. A small 10×10 room is closer to 1.5–2 gallons; add a quart if you're also painting the trim a different color.
How much paint for a 12x12 room?
A 12×12 ft room with 8 ft ceilings has about 384 ft² of wall, so it needs roughly 2 gallons for two coats after deducting a door and window.