Paint Calculator
Estimate gallons or liters of paint needed for a room, including multiple coats.
How to use this tool
- Enter room length, width and ceiling height.
- Add number of doors and windows (subtract their area), or enter opening area directly.
- Set coats (1–3) and coverage per can.
- Choose can size and add cost.
- Calculate gallons/liters and number of cans.
How it works
Wall area = perimeter x height. Subtract openings. Multiply by coats. Divide by coverage per gallon (default 350 sq ft). Round up to whole cans.
Tips
- Two coats for significant color changes; three for dark-to-light.
- Textured walls use 10–20% more paint.
- Subtract openings if the room has huge windows.
Limitations
Does not include trim, or priming over bare/unprimed drywall — add those separately.
Frequently asked questions
How many square feet does a gallon cover?
Most paints cover 350–400 sq ft per gallon per coat. This calculator defaults to 350 and lets you change it.
Do I subtract windows and doors?
It's optional. Many calculators ignore openings to be safe with overspray. Use the subtraction if you want precision.
Should I always allow two coats?
For color changes, yes. The calculator multiplies by the number of coats you enter.