Paint guide
How much does a gallon of paint cover?
Many interior wall paints list roughly 350 to 400 square feet per gallon for one coat on a smooth, sealed surface. That is the number printed on the can. Real walls often get less, and every extra coat uses the full area again.
What the label number means
Coverage, or spread rate, is the area one gallon covers in a single coat at the film thickness the manufacturer intends. It assumes a surface that does not soak up much paint. Sherwin-Williams describes typical interior paint coverage as about 350–400 sq ft per gallon, with the surface and application changing the result.
Why your walls may get less
- Bare drywall, fresh joint compound, and plaster absorb more paint.
- Textured walls have more real surface than their flat measurement.
- Rolling too thin to stretch paint leads to an extra coat later.
- Strong color changes, especially light over dark, often need more coats.
How coverage changes the answer
| Coverage | One coat | Two coats | Buy |
|---|---|---|---|
| 250 sq ft/gal | 1.33 gal | 2.66 gal | 3 gal |
| 300 sq ft/gal | 1.11 gal | 2.21 gal | 3 gal |
| 350 sq ft/gal | 0.95 gal | 1.90 gal | 3 gal |
| 400 sq ft/gal | 0.83 gal | 1.66 gal | 2 gal |
Primer and ceilings
Primer labels often list a lower or wider range than paint because they are designed for porous surfaces. Use the primer calculator with your primer’s own figure. Ceilings use the floor area and are usually a different product; the ceiling paint calculator handles them separately.
Metric coverage
Outside the US, coverage is usually stated in square meters per liter. 350 sq ft per gallon is about 8.6 m²/L. Switch the calculator to metric and it converts both the coverage and the result to liters.
Reference: Sherwin-Williams paint calculator guidance