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.
Assumptions to Check
Before ordering materials, confirm the dimensions, product coverage, waste factor, and local installation requirements for your project. Manufacturer coverage tables and local code rules can change the final quantity, especially for structural work, exterior projects, and irregular layouts.
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