Paint Calculator — Gallons Needed
Enter your total wall area and coats to get the gallons of paint required.
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How it works
gallons = ceil((wall_area_sqft × coats) ÷ coverage_per_gallon)
Paint needed by room size (walls, 2 coats)
| Room (8 ft ceiling) | Wall area | Paint, 2 coats |
|---|---|---|
| 10 × 10 ft | 320 sq ft | 2 gallons |
| 10 × 12 ft | 352 sq ft | 3 gallons |
| 12 × 12 ft | 384 sq ft | 3 gallons |
| 12 × 14 ft | 416 sq ft | 3 gallons |
| 12 × 16 ft | 448 sq ft | 3 gallons |
Assumes 8 ft ceilings, ~350 sq ft per gallon, and no deduction for doors and windows (so it runs slightly generous). Smooth, primed walls cover closer to 400 sq ft per gallon — set coverage to 400 in the calculator for those.
Frequently asked questions
How many square feet does a gallon of paint cover?
About 350–400 sq ft per coat on smooth, primed walls. Textured, porous, or unprimed surfaces absorb more and reduce coverage. Most jobs need two coats for an even finish.
How much paint do I need for a 12×12 room?
A 12×12 room with 8 ft ceilings has about 384 sq ft of wall. Two coats takes roughly 2–3 gallons; the calculator rounds up to whole gallons so you do not run short. Add a quart for trim and touch-ups.
Do I need separate paint for the ceiling?
Yes — ceilings use flat ceiling paint and are not counted in wall area. A 12×12 ceiling (144 sq ft) takes about 1 gallon for two coats.