Paint & interior finishes
How Much Does a Gallon of Paint Cover?
By the HomeCalc USAReviewed against our editorial policyLast updated US units and pricing
A gallon of interior paint covers about 350 to 400 square feet per coat on smooth, primed drywall — the figure on the label. Textured, porous or unpainted surfaces drop that to 250 to 300 square feet. Most rooms need two coats, so a gallon realistically finishes one 12×12 room's walls. Always count coats, not just area, before buying.
Skip the arithmetic: use the Paint Calculator.
Key takeaways
- Label coverage of 400 sq ft per gallon assumes smooth, sealed, previously painted drywall.
- New drywall, heavy texture and dramatic color changes all push coverage down toward 250-300 sq ft per gallon.
- Two coats is the default for a uniform finish; only same-color refreshes over sound paint get away with one.
- Primer is cheaper than paint — prime bare or repaired surfaces instead of burning an extra topcoat.
Realistic coverage by surface
Approximate per-coat coverage for one US gallon of interior latex paint.
| Surface | Sq ft per gallon | Why |
|---|---|---|
| Smooth, primed drywall | 350 – 400 | Label conditions; paint sits on top |
| Previously painted, same color | 375 – 400 | Sealed surface, single refresh coat |
| New bare drywall (unprimed) | 250 – 300 | Paper and mud drink the first coat |
| Textured / orange-peel walls | 250 – 300 | Surface area is greater than it looks |
| Bare plaster or masonry | 200 – 250 | Porous; always prime first |
How many coats do you actually need?
The expensive mistake is skipping primer on new drywall: the first topcoat soaks in unevenly, and you end up applying a third coat of expensive paint to fix what a cheaper gallon of primer would have prevented.
- One coat: same-color refresh over paint in good condition.
- Two coats: the standard for any color change and most repaints.
- Three coats or tinted primer: deep colors (reds, navy) and light-over-dark changes.
- Primer plus two coats: new drywall, patches, stains, or glossy oil paint being switched to latex.
From coverage to gallons: the calculation
- Measure wall area: perimeter × ceiling height, minus about 20 sq ft per door and 15 per window.
- Multiply by the number of coats.
- Divide by a realistic coverage rate — 350 for smooth walls, 275 if textured or thirsty.
- Round up to the next gallon or quart; matching a touch-up batch later is harder than storing a spare quart.
Worked example
A 12 × 15 ft bedroom with 8-ft ceilings has a perimeter of 54 ft, giving 432 sq ft of wall. Subtract a door and two windows (about 50 sq ft) for 382 sq ft. Two coats is 764 sq ft of painting. At 350 sq ft per gallon that is 2.2 gallons — buy two gallons for the walls plus a quart for touch-ups or the closet.
Frequently asked questions
Does one gallon cover a whole room?
Only a small one. A gallon covers roughly 350-400 sq ft per coat, and a modest 12×12 bedroom has about 350-400 sq ft of wall — so one gallon gives you a single coat. For the standard two coats you need two gallons for a room that size.
Is paint-and-primer-in-one worth it?
Over previously painted walls in decent shape, yes — it often gets a color change done in two coats. Over new drywall, stains or glossy oil paint, it is not a substitute for a real primer, which is formulated to seal and bond.
Why did my paint cover less than the label says?
Label coverage assumes a smooth, sealed surface. Texture, unprimed patches, thirsty new drywall and even using a thick-nap roller all increase consumption. Plan with a conservative 300-350 sq ft per gallon and you will rarely run short.
Sources and references
- Paint Quality Institute — application guidance — Coverage and surface preparation reference.