Paint Calculator
A 12 by 10 by 8 foot room with the ceiling, one door, one window, and 41 feet of trim is 2.59 gallons at two coats and 350 square feet per gallon. That orders 3 gallons, or 11 quarts.
Last updated . Room size starts in feet. Switch a length to inches, yards, or meters. Coverage starts at 350 ft² per gallon, the low end of a 350–400 planning range. No price.
Enter the walls, the ceiling, the openings, and the trim. Gallons are that area times the coats, divided by the coverage on the can.
Sheets: drywall calculator. A cement-and-sand coat: plaster calculator. Floor finish: flooring calculator.
Paint for a room
Trim starts at 41 ft, the 44 ft perimeter minus the 3 ft door. It does not change when the room changes. The face starts at 4 in.
350 to 400 ft² per gallon is a labeled planning range, not a brand. The count starts at 350, the low end. Type the number on the can. No price.
Results
How the gallons are counted
Walls = 2 × (length + width) × height. Openings come off the walls only. Ceiling is length × width when it is included. Trim is the length you type times the face width. The 41 ft start is the 44 ft perimeter minus the 3 ft door, and a 4 in face makes 13.67 square feet. Net is 452.67 square feet.
Two coats make 905.33 square feet. Divided by 350 square feet per gallon, that is 2.59 gallons, or 10.35 quarts. The order rounds up: 3 gallons, or 11 quarts. 350 and 400 are the two ends of a planning range. They are not a brand’s coverage. Type the number on the can.
Worked example
Leave every field as it opens. Walls read 352.00 ft² · 32.70 m². Ceiling reads 120.00 ft² · 11.15 m². Openings read 33.00 ft² · 3.07 m². Trim reads 13.67 ft² · 1.27 m². Net reads 452.67 ft² · 42.05 m². With coats reads 905.33 ft² · 84.11 m². Gallons read 2.59 gal. Quarts read 10.35 qt. Order reads 3 gal · 11 qt.
| Case | With coats | Gallons | Quarts | Order |
|---|---|---|---|---|
| 2 coats, 350 | 905.33 ft² | 2.59 gal | 10.35 qt | 3 gal · 11 qt |
| 2 coats, 400 | 905.33 ft² | 2.26 gal | 9.05 qt | 3 gal · 10 qt |
| 1 coat, 350 | 452.67 ft² | 1.29 gal | 5.17 qt | 2 gal · 6 qt |
| No ceiling, 2 coats, 350 | 665.33 ft² | 1.90 gal | 7.60 qt | 2 gal · 8 qt |
| No openings, 2 coats, 350 | 971.33 ft² | 2.78 gal | 11.10 qt | 3 gal · 12 qt |
Frequently asked questions
How much paint for a 12 by 10 room?
Leave the room at 12 ft by 10 ft by 8 ft, the ceiling checked, the door at 3 ft by 7 ft, the window at 3 ft by 4 ft, trim at 41 ft by 4 in, and two coats at 350. Walls read 352.00 ft² · 32.70 m². Ceiling reads 120.00 ft² · 11.15 m². Openings read 33.00 ft² · 3.07 m². Trim reads 13.67 ft² · 1.27 m². Net reads 452.67 ft² · 42.05 m². With coats reads 905.33 ft² · 84.11 m². Gallons read 2.59 gal. Quarts read 10.35 qt. Order reads 3 gal · 11 qt.
What does 400 square feet per gallon change?
Choose 400 ft²/gal. The coverage field becomes 400. Gallons read 2.26 gal. Quarts read 9.05 qt. Order reads 3 gal · 10 qt. The area stays 905.33 ft² · 84.11 m². 350 to 400 is a planning range, not a brand. Type the number on the can.
How much paint with one coat?
Set the coverage back to 350 and the coats to 1. With coats matches the net, 452.67 ft² · 42.05 m². Gallons read 1.29 gal. Quarts read 5.17 qt. Order reads 2 gal · 6 qt.
What if the ceiling is not painted?
Set coats back to 2 and uncheck Include the ceiling. Ceiling reads 0.00 ft² · 0.00 m². Net reads 332.67 ft² · 30.91 m². With coats reads 665.33 ft² · 61.81 m². Gallons read 1.90 gal. Quarts read 7.60 qt. Order reads 2 gal · 8 qt.
What if the openings stay in the wall area?
Check the ceiling and set the door height and the window height to 0. Openings read 0.00 ft² · 0.00 m². Trim stays 13.67 ft² · 1.27 m², because the trim length is its own field. Net reads 485.67 ft² · 45.12 m². With coats reads 971.33 ft² · 90.24 m². Gallons read 2.78 gal. Quarts read 11.10 qt. Order reads 3 gal · 12 qt.
Where does the 41 foot trim come from?
The room perimeter is 2 × (12 + 10) = 44 ft. The door is 3 ft wide, so the starter trim is 41 ft. The face is 4 in, and 41 × 4 ÷ 12 = 13.67 ft². The trim length does not follow the room after you edit it. Type a new length when the room changes.
Is this drywall, plaster, or stain on a roof?
No. This page is wall, ceiling, and trim paint in gallons and quarts. Sheets and joint compound are the drywall calculator. A cement-and-sand coat is the plaster calculator. Shingles are the shingle calculator.