How much does a gallon of paint cover?
Updated August 2026
350 to 400 sq ft per coat, on smooth sealed drywall. Every can in the store says so, and both numbers are true in the way a car's highway mileage is true: achieved under conditions your project may not have. On stucco or a popcorn ceiling the same gallon covers 200.
Where the can's number comes from
The printed rate assumes smooth, sealed, previously painted drywall, a 3/8-inch roller nap, and a painter who isn't mashing the roller dry. Sherwin-Williams and Behr both publish 350 to 400 sq ft per gallon for their interior lines under those conditions, and a second coat over the first one really does hit the top of that range, because the wall is freshly sealed and slick.
Our calculators plan at 350 across the board. The bottom of the honest range costs you at most a leftover quart; the top of it costs you a 6 pm trip in painting clothes.
What each surface really delivers
| Surface | Plan on | Why |
|---|---|---|
| Smooth wall, repaint | 350 to 400 | The can's own conditions |
| Bare drywall, first coat | 275 to 300 | Fresh mud and paper soak up the first pass |
| Orange peel / knockdown | 300 | Texture adds surface the tape measure can't see |
| Popcorn ceiling | 250 | Heavy texture nearly doubles the true surface |
| Rough-sawn wood, shingles | 200 to 250 | End grain and shadow gaps drink paint |
| Stucco, brick, block | 200 to 250 | Porous and rough at once, the worst case |
Running it the other way: paint per square foot
Plenty of people need the inverse, because that is how a materials line on a quote reads. At 350 sq ft per gallon, one square foot of wall takes 0.0029 gallons per coat, which is 0.37 fluid ounces. Two coats doubles it to 0.0057 gallons, so a useful shortcut is 175 sq ft per gallon at two coats: divide your wall area by 175 and round up to whole cans. A 1,000 sq ft wall surface is 5.7 gallons, so six.
Primer runs leaner at 300 sq ft per gallon, and one coat is almost always enough, so a primed and painted wall is roughly 0.0090 gallons per square foot all in. Trim is measured by the running foot rather than the square foot: a quart brushes about 100 linear feet of baseboard per coat. Buying the small can instead? A quart covers less than a quarter of this, because the paint left in the tray is a fixed loss.
The quiet coverage thieves
Nap size matters more than people think: a 3/4-inch cover built for texture carries about a third more paint per pass than a 3/8-inch, which is the point, but it means the texture rates above already assume you switched. Color plays a part too. Bright yellows, oranges, and reds are notoriously weak hiders, and organic reds especially can act like a two-coat color that needs three. And sprayers throw 20 to 30% of the can into the air as overspray; if you spray, buy for it.
The good news: none of this compounds secretly. Pick the right row from the table, use the matching calculator setting, and the math holds. The room calculator has the texture option built in; so does the exterior one. Whole-house interior at the same coverage rates: 2,000 sq ft interior.