How much paint do you need for common room sizes?
A quick reference for standard room sizes, with the assumptions shown so you can adjust for your own room.
Last updated September 20, 2026
These amounts use the same math as the paint calculator. They are a starting point: real rooms have different ceiling heights, more or fewer windows, and walls in different condition.
Assumptions used in the table
- 8-foot ceilings, one door (21 sq ft) and two windows (15 sq ft each)
- Two coats on the walls, at 350 sq ft per gallon
- 10% extra for waste, rounded up to the next quart
- Ceiling paint is one coat at 350 sq ft per gallon, also with 10% extra
Paint needed by room size
| Room size | Wall area (sq ft) | Paintable wall area (sq ft) | Wall paint (gal) | Wall paint to buy | Ceiling paint to buy |
|---|---|---|---|---|---|
| 10 × 10 ft | 320 | 269 | 1.69 | 1 gal + 3 qt | 2 qt |
| 10 × 12 ft | 352 | 301 | 1.89 | 2 gal | 2 qt |
| 12 × 12 ft | 384 | 333 | 2.09 | 2 gal + 1 qt | 2 qt |
| 12 × 14 ft | 416 | 365 | 2.29 | 2 gal + 2 qt | 3 qt |
| 12 × 16 ft | 448 | 397 | 2.50 | 2 gal + 2 qt | 3 qt |
| 14 × 14 ft | 448 | 397 | 2.50 | 2 gal + 2 qt | 3 qt |
| 14 × 16 ft | 480 | 429 | 2.70 | 2 gal + 3 qt | 3 qt |
| 16 × 16 ft | 512 | 461 | 2.90 | 3 gal | 1 gal |
| 16 × 20 ft | 576 | 525 | 3.30 | 3 gal + 2 qt | 1 gal + 1 qt |
| 20 × 20 ft | 640 | 589 | 3.70 | 3 gal + 3 qt | 1 gal + 2 qt |
"Wall paint (gal)" is the exact amount after the waste allowance. "To buy" rounds it up to the next quart.
When your room is different
- Taller ceilings. Wall area grows with height. A 9-foot ceiling adds one-eighth to the wall area compared with 8 feet, before doors and windows.
- More windows or doors. Each extra window takes away about 15 sq ft of wall, and an extra door about 21 sq ft. A room with several large windows may need noticeably less paint than the table shows.
- Textured or new walls. These soak up more paint. Choose the matching wall condition in the calculator. See how much a gallon of paint covers.
- Big color change. Going from dark to light usually needs primer or a third coat.
- L-shaped or odd rooms. Add up the length of every wall you will paint and multiply by the ceiling height. In the calculator, you can enter any length and width that add up to half of that total wall length. This works for walls only, so figure the ceiling from its own area. See how to measure a room for paint.
Common questions
How much paint do I need for a 12 × 12 room?
With the assumptions above, the walls need 2.09 gallons, which you would buy as 2 gallons and 1 quart. Painting the ceiling as well adds about 2 quarts.
How much paint do I need for a 10 × 10 room?
The walls need about 1.7 gallons, so buy 1 gallon and 3 quarts. Add 1 or 2 quarts if you are painting the ceiling.
Does the table include trim, doors or baseboards?
No. Trim, doors and baseboards are usually painted with a different paint and finish, so they are not included here.