Paint calculator
Gallons of paint for the walls of a room, and the ceiling if you want it.
A 12 × 12 ft room with 8 ft walls, one door and two windows takes 2 gallons of paint for two coats.
Measure
You need
333 ft² to paint · 1.90 gallons exactly
Your shopping list
Gallon cans
2 gallons ( L)
5-gallon buckets
1 bucket
Type your price per gallon and per 5-gallon bucket to see which is cheaper.
Everything is calculated in your browser. Nothing you type is sent anywhere.
How it is calculated
- Walls(12 + 12) × 2 × 8 ft = 384 ft²
- Openings384 − 1 × 21 − 2 × 15 = 333 ft²
- Coats333 × 2 = 666 ft²
- Gallons666 ÷ 350 = 1.90, so 2 gallons
Paint for common rooms
8 ft walls, one door, two windows, two coats at 350 ft² per gallon.
| Room | Wall ft² | Gallons, walls | With ceiling |
|---|---|---|---|
| 10 × 10 ft | 269 | 2 | 3 |
| 10 × 12 ft | 301 | 2 | 3 |
| 12 × 12 ft | 333 | 2 | 3 |
| 12 × 14 ft | 365 | 3 | 4 |
| 14 × 16 ft | 429 | 3 | 4 |
| 16 × 20 ft | 525 | 3 | 5 |
Gallons by area to paint
| Area | 1 coat | 2 coats | Gallons to buy |
|---|---|---|---|
| 250 ft² | 0.71 | 1.43 | 2 |
| 500 ft² | 1.43 | 2.86 | 3 |
| 1,000 ft² | 2.86 | 5.71 | 6 |
| 1,500 ft² | 4.29 | 8.57 | 9 |
| 2,000 ft² | 5.71 | 11.43 | 12 |
Frequently asked questions
How much paint do I need for a 12 × 12 room?
2 gallons for two coats on 8 ft walls with one door and two windows (333 ft² of wall). With the ceiling, 3 gallons; with 9 ft walls, 3 gallons.
How many square feet does a gallon of paint cover?
350 to 400 ft² per coat for a premium interior paint on a smooth wall (Sherwin-Williams Cashmere data sheet). The calculator uses 350 so you do not run short; if your can gives another figure, type it in "Coverage per gallon".
How do I calculate the wall area of a room?
Add the length of every wall (the perimeter), multiply by the wall height, then take off the doors and windows. 12 × 12 ft room, 8 ft high: 48 × 8 = 384 ft², minus 21 ft² for a door and 2 × 15 ft² for windows = 333 ft².
Is a 5-gallon bucket cheaper than gallon cans?
Often per gallon, but only if you use most of it. Type both prices in the calculator: it counts the cans and the buckets your room needs and shows which costs less.
How much paint for a ceiling?
The ceiling area is length × width: 144 ft² for a 12 × 12 room, so 0.82 gallons for two coats at 350 ft² per gallon. Choose "Walls and ceiling" to add it.