How many gallons of paint for a 20×20 room?
Quick Answer
A 20×20 room with 8-foot ceilings requires about 3 gallons of wall paint for two coats (after deducting doors and windows) and 1 gallon for the ceiling. Plan on 4 gallons total for a complete two-coat paint job including ceiling, or 2 gallons for walls only.
Quick Reference Table
| Area painted | Paint for 20×20 room (8 ft ceilings) |
|---|---|
| Walls only, 1 coat | 1.5 gallons |
| Walls only, 2 coats | 3 gallons |
| Ceiling only, 1 coat | 0.6 gallons |
| Ceiling only, 2 coats | 1.2 gallons |
| Walls + ceiling, 2 coats | ~4 gallons |
How to Calculate It Yourself
- 1
Wall area: perimeter 80 ft × 8 ft ceiling = 640 sq ft.
- 2
Subtract doors (2 × 20 sq ft = 40 sq ft) and windows (3 × 15 sq ft = 45 sq ft): 640 − 85 = 555 sq ft.
- 3
At 350 sq ft per gallon: 555 ÷ 350 = 1.58 gallons per coat → 3.2 gallons for 2 coats.
- 4
Ceiling: 20 × 20 = 400 sq ft ÷ 350 = 1.14 gallons per coat → 2.3 gallons for 2 coats.
- 5
Total: 3.2 + 2.3 = 5.5 gallons for walls + ceiling, 2 coats. Buy 6 gallons.
Pro Tip
If changing from dark to light color, you may need a primer coat first, adding another gallon. Buying 5-gallon pails saves 20–30% vs. buying individual gallons.
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