How to Calculate Paint Coverage Per Gallon & Liter
When shopping for interior or exterior paint, every paint can label displays a spreading rate statement such as covers 350 to 400 square feet per gallon. Understanding how paint spreading rates translate to actual room surfaces helps homeowners avoid overspending on unneeded paint cans.
Paint spreading rates depend on surface porosity, application methods, and paint quality. Smooth drywall uses significantly less paint than porous concrete block or rough wood siding.
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Standard Paint Coverage Benchmarks
Architectural painting standards define typical spreading rates across standard container sizes:
| Container Size | Volume (Metric) | Smooth Wall Coverage | Textured Wall Coverage |
|---|---|---|---|
| 1 Quart Can | 0.95 Liters | 85 to 100 sq ft | 60 to 75 sq ft |
| 1 Gallon Can | 3.78 Liters | 350 to 400 sq ft | 250 to 300 sq ft |
| 5 Gallon Bucket | 18.9 Liters | 1,750 to 2,000 sq ft | 1,250 to 1,500 sq ft |
How Wall Texture Impacts Paint Spreading Rates
Surface texture acts like a sponge for liquid paint. While smooth primed drywall achieves maximum 400 sq ft per gallon coverage, other substrates require extra paint volume:
- Unprimed Drywall: Soaks up first coats quickly. Reduces coverage to 250 sq ft per gallon. Applying a dedicated primer seal coat first is much cheaper than using premium paint as a primer.
- Textured Plaster & Stucco: Rough orange peel or knockdown textures increase surface area by up to 25 percent. Expect 275 sq ft per gallon coverage.
- Masonry & Brick: Highly porous surface. Expect 200 to 250 sq ft per gallon coverage.
Converting Gallons to Liters for International Projects
One US gallon equals 3.785 liters. In metric markets, paint coverage is measured in square meters per liter. One liter of standard interior wall paint covers approximately 9 square meters per coat.
You can quickly estimate project volumes in both imperial and metric units using our free Paint Calculator.
