Paint gallons by room size
| Room size | Wall area | 1 coat | 2 coats |
|---|---|---|---|
| 8 × 10 ft | 288 ft² | 0.82 gal | 1.65 gal |
| 10 × 10 ft | 320 ft² | 0.91 gal | 1.83 gal |
| 10 × 12 ft | 352 ft² | 1.01 gal | 2.01 gal |
| 12 × 12 ft | 384 ft² | 1.10 gal | 2.19 gal |
| 12 × 14 ft | 416 ft² | 1.19 gal | 2.38 gal |
| 12 × 16 ft | 448 ft² | 1.28 gal | 2.56 gal |
| 14 × 16 ft | 480 ft² | 1.37 gal | 2.74 gal |
| 15 × 20 ft | 560 ft² | 1.60 gal | 3.20 gal |
| 20 × 20 ft | 640 ft² | 1.83 gal | 3.66 gal |
Theoretical coverage using 8-foot walls and 350 ft²/gal before openings, waste or touch-up reserve. Actual coverage varies by paint and surface.
Paint quantity formula
Gallons = net paintable area × number of coats ÷ product coverage per gallon. For a rectangular room, gross wall area is room perimeter × wall height. Subtract doors and windows when appropriate.
Example: 12 × 12 room
A 12 × 12 ft room has a 48 ft perimeter. At 8 ft high, gross wall area is 384 ft². At 350 ft² per gallon, one coat is about 1.10 gal; two coats are about 2.19 gal before openings.
Why actual coverage changes
Porous or textured surfaces, major color changes, application method and the paint itself can affect coverage. Treat 350 ft² per gallon as an example, not a product promise. Use the manufacturer’s stated coverage for the selected paint.
Why the can count can exceed exact gallons
Paint comes in fixed container sizes. A calculated requirement of 2.2 gallons normally cannot be purchased as exactly 2.2 gallons. The Paint Calculator helps translate the project into a practical planning quantity while keeping coats, coverage and openings explicit.
Connect drywall and paint
If the wall is being built or refinished, start with the Wall Framing Guide and Drywall Sheet Guide. Continue through the Walls & Finishes Hub.
Frequently asked questions
How much paint do I need for a room?
Calculate net paintable wall area, multiply by the number of coats, then divide by the coverage rate stated on the paint. Round the shopping quantity up to available container sizes and include any desired touch-up reserve.
How much paint for a 12x12 room?
A 12x12 room with 8-foot walls has 384 square feet of gross wall area. At a planning coverage of 350 square feet per gallon, that is about 1.10 gallons for one coat or 2.19 gallons for two coats before deducting openings.
How many square feet does a gallon of paint cover?
Coverage varies by product and surface. This guide uses 350 square feet per gallon as a planning example, but use the coverage printed by the manufacturer for the paint you purchase.