Wall Paint Calculator
Calculate paint needed for walls, accounting for doors and windows.
How It Works
Wall area = 4 × Length × Height. Paintable = Wall area − Doors − Windows. Gallons = ceil((Paintable × Coats) ÷ 350).
Example
A 20 ft × 8 ft room: 640 sq ft of wall, minus 36 sq ft of doors/windows = 604 sq ft → 4 gallons for 2 coats.
Frequently Asked Questions
Why multiply by 4?
This assumes a rectangular room with four equal walls of the entered length. For irregular rooms, measure each wall.
Should I subtract doors and windows?
Yes, subtract their area to avoid over-ordering. The tool accepts both as inputs.
What is a typical door/window area?
A standard door is about 21 sq ft; a typical window 12–15 sq ft.