Build calculator
How many gallons of paint a room takes
Room size, doors, windows and coats in; gallons out, with the wall area and coverage behind the number.
Data last checked . Every source is listed below.
Paint for this room
2.1 gallons for the walls, 2 coats. Cans are sold in whole gallons, so 3 would cover it.
- Wall area to paint
- 366 sq ftafter taking off doors and windows
- One coat takes
- 1.0 gallons
- Whole gallons
- 3the total rounded up
For information only: not advice, a design or a code ruling. We take care, but our sources can lag and so can we, so a figure may be out of date. Package sizes and prices come from the maker and the store, and codes from the local building authority.
What moves the number
The few things that change the answer the most, in plain terms.
- Coverage on the can
- Makers print a range, such as 250 to 400 sq ft a gallon. Smooth, primed walls reach the high end; rough, dark or unprimed walls fall toward the low end.
- Number of coats
- Each coat needs the same amount of paint again. A big color change or bare drywall often takes a primer coat as well.
- Ceiling height
- Wall area is the distance around the room times the height, so a 10-foot ceiling adds a quarter to the walls of an 8-foot room.
- Openings
- Doors and windows come off the wall area. A room with big windows needs noticeably less than the same room with solid walls.
The working
Step by step, with the numbers from the starting example, so you can check it on paper.
- Distance round the room: 2 x (14 + 12) = 52.0 ft.
- Wall area before openings: 52.0 ft x 8 ft = 416 sq ft.
- Take off 1 door at 20 sq ft and 2 windows at 15 sq ft: 366 sq ft of wall.
- Gallons for the walls: 366 sq ft x 2 coats / 350 sq ft a gallon = 2.1.
- Total 2.1 gallons, or 3 whole gallons.
Try a different case
Each opens the calculator with the numbers filled in.
What we assumed
Where a number is an example, we say so.
- Checked sourceCoverage of 350 sq ft a gallon is the middle of the 250 to 400 sq ft a gallon that Behr prints for its interior lines (Dynasty, Marquee, Premium Plus, Pro i100). Your can may differ; type its figure under More options. Sprayed paint loses some to overspray.
- Our estimateA door is taken as 20 sq ft (3 ft by 6 ft 8 in) and a window as 15 sq ft (3 ft by 5 ft). Your openings may be bigger or smaller.
- Our estimateTrim, baseboards, closets and wall damage are not included, and neither is primer.