How much does a gallon of paint cover?
About 350–400 square feet per coat — here is why the real number is usually the lower one, and how to turn it into the number of cans to buy.
The short answer
One gallon of interior wall paint covers roughly 350 to 400 square feet in a single coat on a smooth, primed, similar-coloured wall. For planning, use 350 sq ft per gallon — it is the figure that holds up on real walls, and it is better to have a little left over than to run out mid-wall.
| Container | One-coat coverage (planning) |
|---|---|
| Quart (0.95 L) | ~85–100 sq ft |
| Gallon (3.79 L) | ~350 sq ft |
| 5 gallons (18.9 L) | ~1,750 sq ft |
| 1 litre | ~10–12 m² |
From coverage to cans
gallons = wall area × coats ÷ coverage per gallon × (1 + loss allowance)
cans = round up (gallons ÷ gallons per can)
Worked example — a 12 × 12 ft room with 9 ft walls, three walls painted, one door and one window removed (287 sq ft of wall), two coats, 350 sq ft/gal, 10% loss:
- 287 × 2 = 574 sq ft of painting
- 574 ÷ 350 = 1.64 gallons
- +10% loss = 1.80 gallons → two 1-gallon cans
Primer is a separate product with its own coverage (often lower on new drywall, around 250–350 sq ft/gal) and usually one coat. Keep it on its own line — the paint calculator and the room planner both do.
Why real coverage runs lower
- New or patched drywall absorbs paint until it is sealed — prime it first.
- Texture (knockdown, orange peel) adds surface area the flat label figure ignores.
- Dark-to-light colour changes can need an extra coat regardless of coverage.
- Spraying loses more to overspray than rolling.
When any of these apply, plan at the low end of the range and add a coat rather than stretching the paint.
Buying for several rooms
Painting several rooms the same colour? Add the areas first and round to cans once — rounding each room separately wastes part-cans. A 5-gallon bucket is cheaper per gallon above about four gallons, but only if you will use it. See buying paint for several rooms, and run the numbers in the paint calculator.
Questions
How much does a gallon of paint cover?
A gallon of interior wall paint covers about 350–400 sq ft in one coat on a smooth, primed surface. Plan for the lower end — 350 sq ft — on new drywall, textured walls, or a big colour change, because those drink more paint. Always check the figure on your can; it is the number that matters.
How much does a quart of paint cover?
A quart is a quarter of a gallon, so roughly 85–100 sq ft in one coat. Quarts are useful for trim, doors, and touch-ups, or when a gallon would leave you with most of a can unused.
How many gallons do I need for two coats?
Multiply your wall area by 2, divide by the coverage on the can, then add a small loss allowance for roller and tray waste. For 350 sq ft of wall at two coats and 350 sq ft/gal: 350 × 2 ÷ 350 = 2 gallons before allowance. The paint calculator does this and rounds to whole cans.
Why does my paint cover less than the label says?
Label coverage assumes a smooth, sealed, similar-coloured surface. New drywall and bare patches absorb more; texture adds surface area; going from a dark colour to a light one needs more coats. Spraying also loses more to overspray than rolling. Treat the label as a best case and prime first where you can.
Do I subtract doors and windows?
Yes — paint covers the wall that is actually there, so subtract each opening. If you are painting the door or trim a different colour, count that separately. The planner handles this per surface so nothing is double-counted.