How many square feet does a gallon of paint cover?
One gallon of interior wall paint covers roughly 350 square feet in a single coat on a smooth, primed surface. Two coats are standard for a colour change, so a gallon realistically covers about 175 square feet of finished wall.
Short version
- The 350 sq ft per gallon figure is an industry standard, not a product specification.
- Texture, porosity and colour change all reduce it — sometimes by half.
- The number that matters for your job is on the product's technical data sheet, not on a blog.
- Buy for two coats. A single coat over a different colour almost never looks finished.
Why 350 square feet is a starting point, not an answer
Every manufacturer publishes a spread rate for each individual product, and those numbers differ. A self-priming premium paint and a contractor-grade flat do not cover the same area per gallon, and neither matches the generic figure. The generic 350 sq ft/gal is useful for a first estimate at the store; it is not what you should hand an estimator.
Publishing a general figure as though it were a specification is the most common error in this trade. If you need the real number for the paint you are buying, read the technical data sheet for that product and that sheen.
What reduces coverage on a real wall
Porous or previously unpainted drywall drinks the first coat. Textured surfaces — knockdown, orange peel, popcorn — have far more surface area than their footprint suggests and can cut coverage by a third or more. Rough exterior substrates such as split-face block or heavy stucco can halve it.
A large colour change, especially over a deep or saturated base, costs a coat regardless of what the can says about hiding. Priming in a tinted primer is usually cheaper than adding a third finish coat.
How to work out what to buy
Measure the perimeter of the room and multiply by the wall height to get gross wall area. Subtract about 20 square feet per door and 15 per average window. Divide by the product's published spread rate, then multiply by the number of coats.
Round up to the next whole gallon and keep the leftover for touch-ups — a later batch will not match exactly, even in the same colour.
Common mistakes
- Buying for one coat because the label says "one-coat coverage" — that claim assumes a similar existing colour and a sealed surface.
- Estimating ceiling and wall paint together. Ceilings are usually flat, walls usually are not, and they are different products.
- Forgetting that trim, doors and ceilings each need their own product and their own quantity.
- Ignoring the primer coat when the surface is bare drywall, patched, or a drastic colour change.
Related questions
Sources
- Sherwin-Williams. Paint calculator and product data sheets (accessed 2026-08-17).
- Benjamin Moore. How much paint do I need (accessed 2026-08-17).
Also asked as
- How many sq ft does a gallon of paint cover?
- How many square feet does gallon of paint cover?
- How many sqft does a gallon of paint cover?
- How many square feet does 1 gallon of paint cover?
- How many sq ft does 1 gallon of paint cover?
- How many sq feet does a gallon of paint cover?
- How many square feet does one gallon of paint cover?
- How many sq ft does one gallon of paint cover?