Paint Calculator
Buy too little and you make a second trip mid-project; too much and it dries out in the garage. Enter the wall area, coats and coverage to get the gallons — minus the doors and windows you are not painting.
Your numbers
Result
- Exact gallons needed
- 2.06
- Net area to paintsq ft
- 360
| Item | Value |
|---|---|
| Area to paint | 360 sq ft |
| Paint needed (2 coats) | 2.06 gal |
| Gallons to buy (rounded up) | 3 |
| Or in quarts | 9 |
How much paint you need
Take the wall area, subtract doors and windows, multiply by the number of coats, and divide by the coverage on the can: gallons = (area − openings) × coats ÷ coverage. A 400 sq ft wall (minus 40 for openings) at 2 coats and 350 sq ft/gal needs 360 × 2 ÷ 350 ≈ 2.06 gallons — so buy 3, or 2 gallons plus a quart.
Coverage varies a lot
The 350 sq ft-per-gallon figure is a typical single coat on a smooth, primed surface. Rough, porous or dark-to-light walls drink more paint and cut coverage. The first coat on new drywall or bare wood always covers less — which is why two coats (or a primer coat) is the norm.
Don’t forget primer and trim
This estimates the wall paint. Bare surfaces, big color changes and stains usually need a primer coat too — calculate it the same way. Trim, ceilings and doors are separate areas with their own (often different) paint, so measure and add them if you are painting them as well.
Frequently asked questions
Sources
- Typical paint coverage (~350 sq ft per gallon per coat)
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