Ceiling Paint Calculator
A ceiling paint calculator divides length × width by 350 sq ft per gallon: a 15 × 12 ft ceiling needs 0.51 gallon a coat, or about 1.03 gallons for two coats.
How much ceiling paint do I need?
A ceiling paint calculator needs just the room’s length and width. Multiply them to get the ceiling area in square feet, then divide by 350, the square feet one gallon covers in a single coat on smooth drywall. A 15 × 12 ft room has a 180 sq ft ceiling, which takes 0.51 gallon per coat. Two coats double that to about 1.03 gallons.
The result is for one coat and is not rounded. Multiply by the number of coats you plan, then round up to the cans you can buy. The cost line applies your price per gallon to the unrounded figure, so it shows the cost of the paint used, not what you pay at the register.
The formula in plain words
- Ceiling area = room length × room width
- Gallons per coat = ceiling area ÷ 350
- Total gallons = gallons per coat × number of coats
A flat ceiling has the same footprint as the floor, so you can measure either one. Closets with their own ceilings count separately; add their length × width.
Worked examples
The single-coat figures match the calculator at its $30 per gallon default.
- Living room, 15 × 12 ft, smooth ceiling**
- Area: 15 × 12 = 180 sq ft
- One coat: 180 ÷ 350 = 0.51 gallon, priced at $15.43
- Two coats: 0.51 × 2 = 1.03 gallons
- Buy: 1 gallon plus 1 quart, or 2 gallons if you want spare for touch-ups
- Open kitchen and dining area, 20 × 16 ft, new drywall**
- Area: 20 × 16 = 320 sq ft
- One coat: 320 ÷ 350 = 0.91 gallon, priced at $27.43
- Two coats over primer: 1.83 gallons, so buy 2 gallons
- Primer: 320 ÷ 300 = 1.07 gallons at the primer’s lower coverage
Ceiling paint for common room sizes
| Room | Ceiling area | 1 coat | 2 coats | Buy for 2 coats |
|---|---|---|---|---|
| 10 × 10 ft bedroom | 100 sq ft | 0.29 gal | 0.57 gal | 1 gallon |
| 12 × 12 ft bedroom | 144 sq ft | 0.41 gal | 0.82 gal | 1 gallon |
| 15 × 12 ft living room | 180 sq ft | 0.51 gal | 1.03 gal | 1 gal + 1 qt |
| 14 × 16 ft family room | 224 sq ft | 0.64 gal | 1.28 gal | 1 gal + 2 qt |
| 20 × 20 ft great room | 400 sq ft | 1.14 gal | 2.29 gal | 3 gallons |
| 30 × 24 ft basement | 720 sq ft | 2.06 gal | 4.11 gal | 5 gallons |
When to expect lower coverage
The 350 sq ft per gallon rate assumes smooth, previously painted drywall. Real coverage drops on:
- Bare drywall and fresh mud, which soak up paint. Prime first.
- Popcorn and knockdown texture, which have more surface than their footprint.
- Dark ceilings going white, which may need a third coat.
- Thick-nap rollers, which hold and deposit more paint per pass.
Ceiling paint versus wall paint
Ceiling paint is usually a flat, thicker formula made to drip less when rolled overhead. It spreads at about the same rate as wall paint, so the 350 sq ft figure works for both. The finish is what differs. A flat ceiling white hides the seams that light from a window rakes across, while a satin wall paint on the ceiling would show every roller lap.
How to measure
Measure wall to wall at floor level in two directions. For an L-shaped room, split it into two rectangles and add the areas. For a vaulted ceiling, measure each sloped plane from wall plate to ridge along the slope, multiply by its length, and add the planes. A vault has more area than the floor below it.
Common mistakes
- Using wall paint coverage for a textured ceiling. Texture can cut coverage by a third.
- Skipping primer over water stains. The stain often shows through two coats of ceiling paint.
- Forgetting the second coat. Ceilings are rolled overhead and thin spots are common. Plan for two unless you are refreshing the same white.
- Buying for the area and not the coats. The calculator gives one coat. Double it yourself.
Related calculators
For the walls in the same room, use the paint calculator. New drywall needs a base coat, which the primer calculator sizes. If you are replacing the ceiling instead of painting it, the drywall calculator counts the sheets.
Frequently asked questions
How much paint do I need for a ceiling?
Multiply the room's length by its width to get the ceiling area, then divide by 350 sq ft per gallon for one coat on a smooth ceiling. A 12 × 12 ft bedroom is 144 sq ft, which is 0.41 gallon per coat. Two coats need 0.82 gallon, so one gallon covers it with a little left for touch-ups.
How is ceiling area different from wall area?
A flat ceiling is one plane the size of the floor, so its area is length × width. Walls are perimeter × height. In a 15 × 12 ft room with 8 ft walls, the ceiling is 180 sq ft while the walls are 432 sq ft before doors and windows, so the ceiling takes well under half the paint the walls do.
Why is flat sheen almost always used on ceilings?
Flat paint scatters light instead of reflecting it. Ceilings are seen at a low angle under light from windows and fixtures, which is exactly when sheen shows roller marks, patched joints, and drywall seams. Flat hides them.
Does popcorn or heavily textured ceiling need more paint?
Yes. Texture adds real surface and soaks up paint, so coverage can drop well below 350 sq ft per gallon. Many painters plan for roughly 30% more paint on heavy texture. A 180 sq ft popcorn ceiling would then need about 0.67 gallon a coat instead of 0.51. Use a thick-nap roller and do not overwork it, or the texture can loosen.
How many coats does a ceiling typically need?
One coat often refreshes a ceiling going white over white. Two coats are usual over new drywall (after primer), a color change, or a dingy ceiling. Water stains and smoke stains should be sealed with a stain-blocking primer first, since paint alone tends to let them bleed through.
Estimates only. Verify quantities with your supplier before purchasing.