How Much Does a Gallon of Paint Cover?
Coverage by surface
| Surface | Sq ft per gallon, one coat |
|---|---|
| Smooth, previously painted drywall | 350–400 |
| Lightly textured drywall (orange peel) | 300–350 |
| Heavy texture (knockdown, popcorn) | 250–300 |
| New drywall, primed | 300–350 |
| Bare drywall, unprimed | 200–250 |
| Smooth wood, trim, doors | 350–400 |
| Rough sawn wood, fencing | 150–250 |
| Concrete block, stucco, brick | 100–200 |
The number on the can — the "spread rate" — is measured on a smooth, sealed test surface. It is a ceiling, not an average. Anything that increases the surface area or absorbs paint reduces it, and texture increases surface area far more than it looks like it should.
The arithmetic
gallons = paintable area × coats ÷ coverage per gallon
For a 14 × 12 ft room with 8 ft walls, one door and two windows, two coats at 350 sq ft per gallon:
- Perimeter 2 × (14 + 12) = 52 ft; wall surface 52 × 8 = 416 sq ft
- Deduct 21 sq ft for the door and 15 each for the windows: 416 − 51 = 365 sq ft
- Two coats: 730 sq ft of coverage
- 730 ÷ 350 = 2.09 gallons → buy 2 gallons plus 1 quart
Five things that quietly cost you paint
- Colour change. A dramatic shift — white over deep red, or any strong colour over white — may need three coats without a tinted primer. Primer is cheaper per gallon than finish paint and covers better.
- Cheap paint. Lower solids content means thinner build per coat, so you use more of it to get the same opacity. Two coats of good paint frequently costs less in total than three of bargain.
- Spraying. Faster, but transfer efficiency is well below brushing and rolling; budget noticeably more material, and considerably more if there is any breeze on an exterior.
- Porous repairs. Fresh joint compound and patched areas drink paint and flash differently in sheen. Spot-prime them.
- Deep bases. Saturated colours are made on bases with less white pigment, which means less hiding power per coat. The richest colours are the ones most likely to need three coats.
Gallons versus quarts
Four quarts make a gallon but cost meaningfully more, so buy gallons for volume and use quarts only for the remainder and for touch-up stock. Buying three gallons when you needed 2.1 leaves you storing most of a gallon; two gallons plus a quart leaves you with a small, useful can.
Trim is usually a quart-scale job: one gallon of trim paint covers roughly 600 linear feet of standard baseboard, so most rooms need far less than a gallon.
Buy it in one trip
Tinted paint varies slightly between mixes. If a room needs three gallons, buy three at once, or box them — pour all the cans into one bucket and mix — so that a shade difference cannot show up as a stripe halfway along a wall.
The paint calculator handles the deductions, coats and can breakdown; set the coverage field to whatever your can states rather than the 350 default if you are painting anything textured.
Enter the room and get the paintable area, the gallons required and the exact combination of cans to buy — doors and windows subtracted, coats and spread rate under your control.
Frequently asked questions
How many square feet does a gallon of paint cover in two coats?
Halve the one-coat figure: about 175 to 200 square feet of wall at two coats on smooth drywall. Coverage is per coat, so two coats over the same wall consumes twice the paint.
Why did my paint cover less than the can claimed?
Spread rates are measured on smooth, sealed surfaces. Texture increases the real surface area, bare or patched areas absorb paint, deep colour bases hide less per coat, and spraying loses material to overspray. Any of those can cut the effective coverage by a quarter or more.
Is one gallon enough for a bedroom?
For one coat on a small bedroom, usually yes. For the two coats a repaint normally needs, a 12 by 12 foot room with 8 foot ceilings takes closer to two gallons for walls alone, plus about a gallon more if you paint the ceiling.
- How Many Coats of Paint Do You Need?
- How Much Primer Do I Need — and Do You Even Need It?
- Paint Sheen Guide: Flat, Eggshell, Satin, Semi-Gloss
- How Much Paint Do I Need for a House Exterior?