Paint guide
How much paint for a 12x12 room?
A 12 × 12 ft room with 8 ft walls usually needs about 2 to 3 gallons of wall paint for two coats, depending on your can’s coverage and how much you leave for doors, windows, and touch-ups. Here is the arithmetic, so you can adjust it to your room.
The worked example
- Perimeter: 12 + 12 + 12 + 12 = 48 ft.
- Gross wall area: 48 × 8 = 384 sq ft.
- Subtract one door and one window, say 20 sq ft in total: 364 sq ft.
- Two coats: 728 sq ft of painting.
- At 350 sq ft per gallon: 728 ÷ 350 = 2.08 gal.
- Add 10% for touch-ups and absorption: 2.29 gal.
- Round up: buy 3 gallons.
350 sq ft per gallon is an example. Many interior paints list roughly 350–400 sq ft. At 400, the same room needs 1.82 gal before the allowance and just over 2.0 gal with it, right on the line between 2 and 3 gallons. Your can decides.
Taller ceilings change it quickly
| Wall height | Gross wall | Net wall | Need | Buy |
|---|---|---|---|---|
| 8 ft | 384 sq ft | 364 sq ft | 2.29 gal | 3 gal |
| 9 ft | 432 sq ft | 412 sq ft | 2.59 gal | 3 gal |
| 10 ft | 480 sq ft | 460 sq ft | 2.89 gal | 3 gal |
What about the ceiling?
The ceiling of a 12 × 12 room is 144 sq ft. Two coats at 350 sq ft per gallon with a 10% allowance comes to 0.91 gal, so one gallon of ceiling paint. Estimate it separately with the ceiling paint calculator because it is usually a different product.
What would change the answer
- One coat instead of two roughly halves the paint.
- New drywall or a dramatic color change may need primer first.
- Textured walls lower the coverage per gallon.
- Large windows or a wall of closet doors reduce the paintable area.
Pricing it out? The paint cost calculator uses the same numbers with your price per gallon.