Paint for a 12 × 15 ft room
This is a large bedroom or a living room. With 8 ft ceilings the four walls have 432 ft² of surface, and after deducting one door (21 ft²) and two windows (30 ft²) there are 381 ft² to paint. The ceiling is 180 ft².
How the number of coats changes it
| Coats | Wall gallons | Buy for walls | Ceiling gallons | Buy for ceiling |
|---|---|---|---|---|
| 1 coat | 1.09 | 1 gallon + 1 quart | 0.51 | 3 quarts |
| 2 coats | 2.18 | 2 gallons + 1 quart | 1.03 | 1 gallon + 1 quart |
| 3 coats | 3.27 | 3 gallons + 2 quarts | 1.54 | 1 gallon + 3 quarts |
If your ceilings are taller
| Ceiling height | Wall area | Gallons (2 coats) | Buy |
|---|---|---|---|
| 8 ft ceilings | 432 ft² | 2.18 | 2 gallons + 1 quart |
| 9 ft ceilings | 486 ft² | 2.49 | 2 gallons + 2 quarts |
| 10 ft ceilings | 540 ft² | 2.79 | 3 gallons |
If your walls are rough or your paint covers less
The label on your can gives its coverage. Rough or textured walls and dark colors cover less, so the amounts go up:
| Coverage | Gallons (2 coats) | Buy |
|---|---|---|
| 250 ft² per gallon | 3.05 | 3 gallons + 1 quart |
| 300 ft² per gallon | 2.54 | 2 gallons + 3 quarts |
| 350 ft² per gallon | 2.18 | 2 gallons + 1 quart |
| 400 ft² per gallon | 1.91 | 2 gallons |
Trim, tape and prep
The room is 54 ft around. Taping both the ceiling line and the baseboard is 108 ft of painter's tape, which is 1 roll of 60 yard tape. A quart of trim paint usually covers the baseboards and window and door casings for a room this size, and a gallon of primer is worth having for stains and patches.
Paint one wall at a time from the ceiling down, "cut in" the edges with a brush before rolling, and keep a wet edge to avoid lap marks. Let the first coat dry fully before the second, as the can directs.
A 12 × 15 room: the ceiling needs just over one can
A 12 × 15 ft room measures 54 ft around, which leaves 381 sq ft of wall once a door and two windows are taken out. Two coats use 2.18 gallons on the walls (2 gallons + 1 quart). The ceiling is 180 sq ft and takes 1.03 gallons for two coats.
That ceiling figure is the awkward one, a shade more than a single gallon. A white ceiling being repainted white often covers in one coat, which the coats table above puts at about half that, so buy one gallon of ceiling paint, do the first coat and judge it dry before you go back for more. For the walls, pour the cans into one bucket and stir them together so the 15 ft walls do not change tone where one can ends.
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Tools & materials for this project
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Frequently asked questions
How many gallons of paint do I need for a 12x15 room?
With 8 ft ceilings, one door, two windows and two coats at 350 ft² per gallon, the walls need 2.18 gallons, so buy 2 gallons + 1 quart. If you also paint the ceiling, add 1.03 gallons (1 gallon + 1 quart).
How much paint for the walls and ceiling of a 12x15 room?
Walls and ceiling together need about 3.21 gallons for two coats. That is 3 gallons + 1 quart if you use the same paint on both, though ceilings are usually painted with a separate flat ceiling paint.
How much primer do I need for a 12x15 room?
One coat of primer over the same walls is about 1.09 gallons (1 gallon + 1 quart). Primer often covers a little less than paint on bare surfaces, so check the can.
Related sizes and guides
Estimates only. Results assume standard materials and simple shapes. Supplier products vary, and the final call on quantity, structure and safety is yours. Check your local code and your supplier's guidance before ordering.