Paint calculator
Enter the room, the coats and the coverage on the can. Jobmath gives the gallons to buy.
How it's calculated
Each step, in the order Jobmath runs it.
| Step | Formula |
|---|---|
| Wall area | 2 × (length + width) × wall height − doors and windows |
| Ceiling area | Length × width |
| Gallons | Area × coats ÷ coverage per gallon |
| To buy | Walls + ceiling, rounded up to whole gallons |
What changes coverage
The coverage on the can assumes a smooth, sealed surface.
| Surface | Effect |
|---|---|
| New drywall or bare wood | Soaks up paint; primer first, or plan an extra coat |
| Dark color over light, or light over dark | Often needs one more coat |
| Rough stucco or block | Uses more paint per square foot than the can lists |
| Smooth, previously painted wall | Closest to the coverage on the can |