Paint Calculator
Calculate how many gallons of paint you need for a room.
Enter your numbers and select Calculate to see results.
About This Calculator
This calculator estimates how many gallons of paint you'll need to paint a room, based on wall dimensions, standard door/window deductions, and the number of coats — plus the estimated material cost.
How This Is Calculated
Gallons = (Wall Area − Doors − Windows) × Coats ÷ 350 sq ft per gallon
A 60 ft perimeter, 9 ft walls, 2 doors, 3 windows, 2 coats needs about 3 gallons of paint.
Assumptions
- Standard door deduction: ~21 sq ft. Standard window deduction: ~15 sq ft.
- Standard paint coverage: ~350 sq ft per gallon per coat — check your specific paint's label for exact coverage.
Frequently Asked Questions
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Last updated January 15, 2026. Results are estimates for informational purposes only — read our disclaimer.