One gallon of interior paint covers roughly 350–400 square feet of smooth wall in a single coat.
Whether you’re touching up one wall or repainting a bedroom, the square footage math behind a gallon of interior paint determines how many cans you haul home from the store. The standard estimate for one gallon on smooth, primed drywall sits at 350–400 square feet per coat, but texture, porosity, and color shifts can shrink that number quickly.
The Standard Coverage Rate For One Gallon
Sherwin-Williams states that a gallon of paint typically covers about 350–400 square feet, and notes that a little more than a gallon may be best depending on wall texture and desired coverage. That range applies to smooth, primed interior walls in a single coat.
Field guidance from professional painters matches that figure. Standard interior latex paint lands at about 350–400 square feet per gallon on smooth, primed drywall. Manufacturer coverage figures represent rated or typical coverage, not a guaranteed result in every room—actual yield depends on how the paint goes on and what surface it touches.
How Wall Texture And Surface Change The Math
Textured walls eat paint. A textured surface lowers coverage to roughly 300–350 square feet per gallon because the ridges and valleys trap extra paint. Primer also covers less than finish paint on the same surface, since it soaks into bare drywall or porous patches.
Several surface factors reduce how far a gallon goes:
- Bare drywall absorbs more paint than a primed or previously painted wall.
- Dark-to-light color changes usually demand a second or even third coat for full hide.
- Unprimed, heavily absorbent surfaces pull paint deeper into the material.
- Orange peel, knockdown, or popcorn texture each add surface area that consumes more paint.
Two coats are often needed for complete coverage even when the nominal square footage fits within one gallon’s range. A room that measures 400 square feet of wall area can still need two gallons if the first coat doesn’t fully hide the surface.
Estimating A 10×10 Room (And What A Gallon Actually Finishes)
A 10-by-10-foot room has about 100 square feet of floor space, but the wall coverage depends on ceiling height and openings. Here’s the practical breakdown for a standard 8-foot ceiling room:
| Wall Area (10×10 room, 8-ft ceiling) | Approx. Square Feet | Gallons For One Coat |
|---|---|---|
| Total wall perimeter | 320 sq ft | About 1 gallon |
| Minus doors and windows (typical) | −40 to −60 sq ft | 3/4 gallon or less |
| Textured walls (reduced coverage) | ~300 sq ft per gallon | Slightly more than 1 gallon |
| Two coats, smooth walls | 640 sq ft total | About 2 gallons |
Trim, doors, and windows subtract from the paintable surface, so a single gallon often completes one coat on a small bedroom with typical openings. Add ceiling painting and the estimate climbs.
If you’re choosing the paint itself for a small room, our tested roundup of the best 1-gallon interior paints compares coverage, finish, and value across top brands.
Planning Your Paint Purchase
Start with 350–400 square feet per gallon as the baseline for interior walls. Reduce that estimate when walls are textured, unprimed, dark, or heavily absorbent. Increase it when trim, doors, windows, or multiple coats are part of the job.
For a precise number on a specific room, use the Sherwin-Williams paint calculator, which accounts for room dimensions, openings, and coat count. Buying an extra gallon beats running out mid-roller—unused paint in a sealed can stores fine for touch-ups later.
When in doubt, round up. Coverage figures are rated estimates, not promises, and a second coat often makes the difference between a patchy wall and a finished room.
FAQs
How many square feet does a quart of paint cover?
A quart of interior paint typically covers about 87–100 square feet per coat, which is roughly one-quarter of a gallon’s rated coverage. That’s enough for a single accent wall, a small bathroom, or touch-up work. Texture and porosity still apply—a quart goes less far on textured or unprimed surfaces.
Is one gallon enough for a bedroom?
Yes, for most small to mid-size bedrooms in a single coat. A typical 10×10 room with 8-foot ceilings and standard windows needs less than a gallon per coat. For two coats on the same room, plan on about two gallons, especially if you’re making a dramatic color change.
Should I buy more paint than the calculator says?
Adding 10–20% extra is a safe margin for textured walls, touch-ups, or a slightly thicker application. Paint calculators assume smooth, primed surfaces at rated spread rates. Unprimed drywall and heavy textures can consume noticeably more, so a small buffer prevents a second store run mid-project.
References & Sources
- Sherwin-Williams. “Paint Calculator.” Official coverage tool for estimating gallons needed by room size and surface.
