Construction calculator
Paint Calculator
Estimate paint needed for interior rooms using wall dimensions, coats, coverage per gallon, and door or window deductions.
Paint estimate
Paint Calculator
Paint to buy
2 gal
Estimated use is 1.78 gallons.
Wall area
352 sq ft
Before subtracting openings
Paintable area
312 sq ft
After doors/windows
Coated area
624 sq ft
Paintable area x coats
Common Tools Used for Project Measurements
Project calculators usually need room dimensions, surface area, package coverage, or product label values.
Tape measure
Laser distance measurer
Level
Product coverage label
Notebook or floor plan
Keep measurements in one unit while entering values, then use the result as a planning estimate.
Formula
gallons = paintable wall area x coats / coverage per gallon
Coverage varies by paint type, wall texture, primer, color change, and surface condition. Round up before buying.
Common Examples
| Input | Estimate |
|---|---|
| 12 ft x 10 ft room, 8 ft walls, 2 coats | About 1.11 gallons before rounding |
| 350 sq ft/gallon coverage | Common planning estimate |
| Subtract 40 sq ft openings | Allows for doors and windows |