How many gallons of paint for a 12×12 room?
Quick Answer
A 12×12 room with 8-foot ceilings needs approximately 1 gallon of paint per coat for the walls, or 1.5–2 gallons for two coats. One gallon of paint covers roughly 350–400 square feet. After subtracting a standard door and two windows, the net wall area is about 320–340 square feet.
Quick Reference Table
| Room Size | Paint Needed (2 coats) |
|---|---|
| 10×10 ft | 1.5 gallons |
| 12×12 ft | 1.5–2 gallons |
| 12×15 ft | 2 gallons |
| 14×14 ft | 2–2.5 gallons |
| 15×20 ft | 2.5–3 gallons |
| 20×20 ft | 3–4 gallons |
How to Calculate It Yourself
- 1
Calculate wall area: add up all four wall lengths, multiply by ceiling height. For 12×12 with 8 ft ceilings: (12+12+12+12) × 8 = 384 sq ft.
- 2
Subtract openings: deduct ~21 sq ft per door and ~15 sq ft per window. One door + two windows = 51 sq ft. Net area: 384 − 51 = 333 sq ft.
- 3
Divide by coverage: one gallon covers 350–400 sq ft. 333 ÷ 375 = 0.89 gallons per coat.
- 4
Multiply by coats: for two coats, 0.89 × 2 = 1.78 gallons. Round up to 2 gallons.
Pro Tip
Buy paint in the larger size when you're close to the boundary — a quart costs about 40% of a gallon but only covers 25%. If you need 1.3 gallons, buy 2 gallons rather than 1 gallon + 1 quart.
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