Paint Calculator
How much paint do you need? Measure your walls, subtract the doors and windows, and get gallons to buy plus an estimated cost. Fast, free, and your numbers never leave this page.
Estimate your paint
Walls
The ceiling is painted at the same coat count you choose below.
Doors and windows to skip
A standard interior door is about 21 sq ft and a typical window about 15 sq ft. Adjust either if yours differ.
Coats and primer
Coverage and price
Most latex paints cover 350 to 400 sq ft per gallon on smooth walls. Porous or textured walls cover less, so use the lower number there.
How it works
- Enter each wall's width and height. Add as many walls as you need.
- Count doors and windows so their area is subtracted from the total.
- Choose one or two coats, and add primer if you are painting bare drywall.
- We divide the total paintable area by your coverage rate, then round up to whole gallons. Paint is sold by the gallon, and the extra covers touch-ups later.
Why trust this estimate
The math follows the industry standard: most latex wall paints list 350 to 400 sq ft per gallon for one coat on smooth, previously painted surfaces. Porous, textured, or bare surfaces drink up more paint, which is why the coverage number is editable. Primer covers roughly 300 sq ft per gallon. The gallon quantities round up because you cannot buy a fraction of a can, and a leftover can is exactly what you want for future touch-ups.
Free to use, no sign up, and nothing leaves your browser.