20×20 room: paint by wall height
| Wall height | Paintable sq ft | Gallons (2 coats) | Buy |
|---|---|---|---|
| 8 ft | 590 | 3.37 | 4 |
| 9 ft | 670 | 3.83 | 4 |
| 10 ft | 750 | 4.29 | 5 |
1 door and 2 windows deducted; 350 sq ft per gallon.
Worked example
Perimeter: 2 × (20 + 20) = 80 ft. With 8 ft walls: 640 sq ft, minus 20 (door) and 30 (two windows) = 590 sq ft. Two coats: 1180 ÷ 350 = 3.37 gallons. The ceiling adds 400 sq ft per coat (about 2.29 gallons for two coats).
Frequently asked questions
How many gallons to paint a 20×20 room?
About 3.37 gallons for two coats on 8 ft walls (buy 4).