Ceiling Paint Calculator
Enter a ceiling's length and width, its slope and the area one gallon covers, and get the ceiling paint rounded up once to whole quarts, with the gallon cans they make.
A ready-made setup of the Paint Calculator.
Estimates for planning, not professional advice. Read the full notice.
Example: a flat twelve by fourteen foot ceiling
0.42 gal
- Ceiling area 168 ft²
- Paint bought, whole quarts 0.5 gal
Estimate for planning, from what you entered and the product data shown. Check product labels and your supplier before you buy.
Your project
Enter a size to see your total.
Each product is rounded up once for the whole project, so the total can be less than the items bought alone added together. A line counted from a cut layout (sheets, boards or tiles laid out piece by piece) is counted for each item and added.
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| Item | Size | Buy |
|---|
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Worked example: a flat twelve by fourteen foot ceiling
Show the working
- Ceiling area: length times width, with no slope 14 ft × 12 ft = 168 ft²
- Paint: area times coats, divided by the area one gallon covers 168 ft² × 1 coat ÷ 400 ft² = 0.42 gal
- Round up once, to whole quarts, then pack them into pails, gallons and quarts 0.42 gal = 0.5 gal
Assumptions
The figures behind the example. Sourced figures link to their source below; a default is a starting value to check against your label or supplier.
| Assumption | Value | Details and changes |
|---|---|---|
| Coats of paint | 2 coats[1] | |
| Default Benjamin Moore recommends two coats for its interior paint. | ||
| Ceiling paint coverage | 400 ft²/gal | |
| Default Not read from a maker's own sheet. Check your label or supplier. | ||
Feet and inches, like 12' 6"
The example ceiling at each slope
Ceiling paint for a ceiling sized like the example, at four slopes, one coat
| Slope (rise over twelve inches) | Slope factor | Ceiling area | Paint, exact | Cans bought, as quarts |
|---|---|---|---|---|
| Flat | 1 | 168 ft² | 0.42 gal | 2 × 1 qt cans |
| Two in twelve | 1.014 | 170.32 ft² | 0.43 gal | 2 × 1 qt cans |
| Four in twelve | 1.054 | 177.09 ft² | 0.44 gal | 2 × 1 qt cans |
| Six in twelve | 1.118 | 187.83 ft² | 0.47 gal | 2 × 1 qt cans |
A sloped ceiling is longer than its floor. Its area is the floor area times the slope factor of the rise over twelve inches.
Questions
Is ceiling paint covered the same as wall paint?
The calculator keeps a separate coverage line for the ceiling because makers print different rates for different paints. The ceiling rate here is an input you can change, not a sourced figure, so check the can.
How do I count a sloped ceiling?
Choose the slope as the rise over twelve inches. The area is the floor area times the slope factor for that rise, shown for four slopes in the table.
Where does the number of coats come from?
The number of coats is your choice: one, two or three. The assumptions row names Benjamin Moore, whose data sheet says how many coats it recommends for its interior paint. Product names are trademarks of their owners. HoneyDoMath is not affiliated with, sponsored by or endorsed by these makers.
Sources (1)
-
Regal® Select Premium Interior Paint & Primer Semi-Gloss N551, product data sheet (opens in new tab), Benjamin Moore & Co., N551 US 062025 (data sheet, © 2022, 2025).
Manufacturer data.
“While the high quality of our products sometimes makes one‐coat coverage achievable, Benjamin Moore® recommends two coats to achieve full color development and to optimize performance. On bare substrates, two coats are recommended; previously painted surfaces can be finished with 1 or 2 coats.”
Per Benjamin Moore's data sheet, checked Nov 12, 2026. Figures and codes change; verify with the source. Back to where this is used (Source 1)
These are summaries of what the sources say, not professional advice. Codes and product data change. Check with your building department and the product label about your own project.
Sources
- [1] Benjamin Moore, Regal® Select Premium Interior Paint & Primer Semi-Gloss N551, product data sheet. Checked November 12, 2026. https://media.benjaminmoore.com/WebServices/prod/assets/production/datasheets/TDS_0551/N551%20TDS%20US%20OKF.pdf