Paint Guide · 2 min read
How much paint for a 12×12 room?
A 12×12 room with 8-ft walls, one door and two windows needs 2 gallons for two coats — 333 sq ft of paintable wall at 350 sq ft per gallon.
A 12×12 room is the size people use as the reference "one room" — and for good reason. With eight-foot walls, a door and two windows, it needs 2 gallons for two coats, which is exactly what a paint store will tell you. The planner shows the deductions so you can check.
Gallons by ceiling height and coats
One door and two windows deducted; 350 sq ft per gallon on smooth walls; rounded up to whole gallons.
| Ceiling | 1 coat | 2 coats | 3 coats | Wall area |
|---|---|---|---|---|
| 8 ft | 1 | 2 | 3 | 333 sq ft |
| 9 ft | 2 | 3 | 4 | 381 sq ft |
| 10 ft | 2 | 3 | 4 | 429 sq ft |
Don't forget
Primer. Going light over dark, or painting new drywall, add 2 gallons of primer. Ceiling. A flat ceiling paint for this room is 1 gallon at one coat. Texture. Orange-peel walls use about 10% more paint, knockdown about 20%; the planner adjusts for it.
A 12×12 room with nine-foot ceilings is the one that catches people out: two coats climb to 2.2 gallons, so you need three cans or a gallon plus a quart.
Other room sizes
10×10 room · 10×12 room · 12×12 room · 12×14 room · 14×16 room · 15×20 room
Last updated 2026-09-03. Method: how we calculate.