A gallon of wall paint typically covers 350 to 400 square feet for one coat on a smooth, previously painted wall. A quart covers about 100 sq ft, and a gallon of primer about 250 to 400 sq ft, toward the low end on new drywall. Most rooms get two coats, so plan on roughly one gallon for every 175 to 200 sq ft of wall. Rough, porous or bare surfaces drink more.
The paint calculator measures the walls for you, takes out doors and windows, and converts the result into gallons and quarts.
Average paint coverage per gallon
| Product | Typical coverage | Per |
|---|---|---|
| Wall paint | 350 to 400 sq ft | 1 gallon, one coat |
| Wall paint | About 100 sq ft | 1 quart, one coat |
| Primer | 250 to 400 sq ft | 1 gallon |
The spread on the label assumes a smooth, sound surface and the recommended application. Our calculator uses 350 sq ft per gallon, the lower end of the range, so estimates lean toward having a little paint left over rather than running out.
Coverage on smooth, textured and porous surfaces
- Smooth, previously painted drywall gets close to the label coverage.
- Textured walls and ceilings (orange peel, knockdown, popcorn) have more surface area than their flat measurements suggest, and the roller has to push paint into the texture. Expect noticeably lower coverage.
- New drywall, bare wood and masonry absorb the first coat. Prime first; the primer has its own, lower coverage.
- Big color changes may need an extra coat no matter how good the paint is.
Application method matters too. Rollers with a thicker nap hold and deposit more paint, and spraying loses some paint to overspray.
How multiple coats affect paint quantity
Coverage is per coat, so two coats need twice the paint. A wall area of 365 sq ft takes:
| Coats | At 350 sq ft/gal | At 400 sq ft/gal |
|---|---|---|
| 1 coat | 1.04 gal | 0.91 gal |
| 2 coats | 2.09 gal | 1.82 gal |
Worked example: a 12 × 14 ft bedroom
- Wall area. Perimeter 2 × (12 + 14) = 52 ft, times an 8 ft wall height = 416 sq ft.
- Subtract openings. One 3 × 7 ft door (21 sq ft) and two 3 × 5 ft windows (15 sq ft each) leave 416 − 21 − 30 = 365 sq ft.
- Two coats. 365 × 2 = 730 sq ft of painting.
- Gallons. 730 ÷ 350 = 2.09 gallons. With 5% extra for touch-ups, 2.19 gallons.
- What to buy. Two gallons plus a quart covers it with a little to spare. Three gallons gives you more spare paint.
The ceiling is a separate job: 12 × 14 = 168 sq ft, which takes about 1 gallon of ceiling paint for two coats at 350 sq ft per gallon.
Paint needed by wall area
| Wall area | 1 coat (350–400 sq ft/gal) | 2 coats (350–400 sq ft/gal) |
|---|---|---|
| 200 sq ft | 0.5 to 0.6 gal | 1.0 to 1.1 gal |
| 400 sq ft | 1.0 to 1.1 gal | 2.0 to 2.3 gal |
| 600 sq ft | 1.5 to 1.7 gal | 3.0 to 3.4 gal |
| 800 sq ft | 2.0 to 2.3 gal | 4.0 to 4.6 gal |
How to avoid buying too much or too little
- Measure walls, not floor area. Room size in square feet tells you about the floor, not the walls. Multiply the perimeter by the height.
- Read the can. Coverage varies by product and sheen; use the number printed on the label when you have it.
- Buy one batch for the whole room. Tinted paint can vary slightly between batches. If you need several gallons, mixing them together in a bucket (boxing) keeps the color even.
- Use quarts for the last bit. If you are a fraction over a whole gallon, a quart is often enough.
- Keep some for touch-ups. Label the leftover can with the room and the date.
Covering walls with paper instead? The wallpaper calculator counts rolls by full-height strips.
Sources
- Sherwin-Williams Paint Calculator (coverage per gallon, quart and primer)
