Paint Calculator
Estimate how many gallons of interior paint you need for a room, based on wall area minus standard door and window deductions.
- Paintable wall area
- 301 sq ft
- Paint needed
- 1.72 gal
- Recommended purchase
- 2 gallons
How this is calculated
Wall area = 2 × (length + width) × height. Paintable area = wall area − (doors × 21 sq ft) − (windows × 15 sq ft). Gallons = paintable area × coats ÷ 350 sq ft per gallon.
Assumptions
- Each door deducts 21 sq ft; each window deducts 15 sq ft.
- One gallon of paint covers 350 sq ft per coat.
- Deductions never reduce the paintable area below 0.
- Recommended purchase is rounded up to whole gallons.