Free Paint Calculator

Find out exactly how much paint you need for any room. Enter your wall dimensions and get precise paint quantity estimates including doors and windows.

Paint & Wall Square Footage Calculator

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Paint needed

How to Use the Paint Calculator

Measure your room's length, width, and wall height. Enter the number of doors and windows to subtract their area. Select how many coats you plan to apply.

  • Standard door: ~21 sq ft (3' x 7')
  • Standard window: ~15 sq ft (3' x 5')
  • Paint coverage: 1 gallon covers ~350 sq ft

Paint Coverage Formula

Total Area = Perimeter × Wall Height
Paint Needed = (Total Area - Doors & Windows) ÷ 350 × Coats

Frequently Asked Questions

Measure the wall's width and height, multiply them for square footage, then divide by 350. For a 12' x 8' wall with one coat: 96 ÷ 350 = 0.27 gallons (about 1 quart).
This calculator estimates wall paint only. Ceilings typically take 1-2 gallons depending on room size.
Buy 10% extra for waste, touch-ups, and future repairs. If the calculator says 1.2 gallons, buy 1 gallon and 1 quart.