Paint Calculator
Estimate the total gallons required for your interior or exterior painting project. Professional coverage and sheen optimization.
Paint Required
Total Surface Area
Coverage Rate
Coverage Estimations
One gallon of standard interior paint typically covers between350 and 400 square feet. This coverage varies based on surface porosity; new drywall or masonry will absorb more paint, often requiring a dedicated primer to ensure true color representation.
Flat & Matte
Ideal for ceilings and formal rooms. It hides surface imperfections effectively but is difficult to clean, making it unsuitable for high-traffic or damp areas.
Semi-Gloss & Satin
The standard for kitchens and bathrooms. Highly durable, moisture-resistant, and easy to scrub, though it highlights wall flaws and uneven textures.
Coverage Equation
Gallon Estimation Logic
Gallons = [ Total Surface Area ÷ 350 ] × Coats
Where Total Surface Area = [ 2 × (L + W) × H ] - Deductions (Doors/Windows).
Professional Rules
- Standard Door: Subtract ~21 ft²
- Standard Window: Subtract ~15 ft²
- Double Window: Subtract ~30 ft²
- Porous surfaces require 20% more paint
The Two-Coat Rule
Even with high-quality "one-coat" labeled products, professional painters almost always apply two coats. This ensures uniform color depth, hides the previous wall color completely, and provides a much more durable wear surface.
Material Requirements (2 Coats)
Room Size (ft) Total Area (ft²) Gallons Required 10' x 10' x 8' 320 1.8 12' x 12' x 8' 384 2.2 15' x 15' x 8' 480 2.7 20' x 20' x 8' 640 3.7 Frequently Asked Questions