How Much Paint Do I Need for a Room?
You’ll need about 2 gallons for the walls of a typical 12 × 12 ft bedroom with two coats. Divide the wall area × coats by about 350 sq ft per gallon.
The Formula
Sherwin-Williams’ method is to divide the area you’re painting by the coverage per gallon. For walls:
Gallons = (room perimeter × wall height − doors − windows) × coats ÷ coverage per gallon
HomeGuide puts typical coverage at 300–400 sq ft per gallon; the tables below use 350.
Paint for Common Rooms
The table assumes two coats, one door (20 sq ft), two windows (15 sq ft each), and 350 sq ft per gallon:
| Room | Wall height | Wall area | Paint | Buy |
|---|---|---|---|---|
| 10 × 10 ft | 8 ft | 270 sq ft | 1.54 gal | 2 gallons |
| 12 × 12 ft | 8 ft | 334 sq ft | 1.91 gal | 2 gallons |
| 12 × 14 ft | 8 ft | 366 sq ft | 2.09 gal | 2 gallons + 1 quart |
| 14 × 16 ft | 8 ft | 430 sq ft | 2.46 gal | 2 gallons + 2 quarts |
| 20 × 15 ft | 9 ft | 580 sq ft | 3.31 gal | 3 gallons + 2 quarts |
Ceilings are extra: a 12 × 12 ft ceiling is 144 sq ft, under a gallon for two coats.
What Changes How Far a Gallon Goes
- Surface. New drywall, patched walls, texture, and masonry soak up paint. Prime first.
- Color change. Going from dark to light, or the reverse, can take an extra coat.
- Product. The coverage on the can is the best guide; thicker paints and primers vary.
- Tools. Thick roller naps and sprayers use more paint.
Cost
Paint costs about $15–$50 a gallon (HomeGuide). The paint calculator works out gallons, quarts, and cost for your room’s exact size.
Frequently Asked Questions
How Much Does a Gallon of Paint Cover?
HomeGuide puts it at 300–400 sq ft per coat. Check the can; coverage varies by product and surface.Is One Gallon of Paint Enough for a Bedroom?
It usually isn’t enough for two coats. A 10 × 10 ft room with 8 ft walls has about 270 sq ft of wall after a door and two windows, which is about 1.5 gallons for two coats.Should I Buy Quarts or Another Gallon?
Quarts are handy for a small remainder, but three quarts usually cost about as much as a gallon. Leftover paint is useful for touch-ups.Sources
Prices are national ballparks checked October 2026. Local prices vary.