Paint Calculator
Enter your wall area and the number of coats. One gallon covers about 350 ft² per coat. The calculator subtracts nothing for doors and windows by default — adjust the area if you have large openings.
Your measurements
ft²
$
Coverage
- Wall area
- 400 ft²
- Coats
- 2 coats
- Total coverage
- 800 ft²
Buy this
- Gallons (exact)
- 2.29 gal
Paint needed
3 gal
Estimates only. Order a little extra for waste and verify against your supplier's coverage figures.
The formula
Gallons = (Wall area × Coats) ÷ 350 ft² per gallon
Example: 400 ft² of wall × 2 coats = 800 ÷ 350 = 2.3 → 3 gallons.
How it works
- 1Multiply wall area by the number of coats for total coverage.
- 2Divide by 350 ft² (the coverage of one gallon) and round up.
- 3Buy a little extra for touch-ups — paint batches are hard to match later.
Frequently asked questions
Does one gallon really cover 350 square feet?
That's the typical figure for smooth, primed walls. Rough or porous surfaces and dark-to-light color changes reduce coverage, so round up.