Paint Calculator

Estimate gallons of paint needed for your room. Subtract doors and windows, choose number of coats, and set coverage per gallon.

Typical: 350-400 sq ft/gal

Paint Needed
gallons
Total Wall Area
sq ft
Paintable Area
sq ft

Formula

Gallons = (Paintable Area × Coats) ÷ Coverage per Gallon

Paintable area = total wall area (perimeter × height) minus door and window openings. Standard coverage is about 350-400 sq ft per gallon for smooth walls.

FAQ

Two coats are standard for most interior walls. Use three coats when painting over dark colors with a lighter shade, or when using paint without built-in primer.
Yes. Rough or textured surfaces can reduce coverage by 20-30%. Lower the coverage setting to about 250-300 sq ft/gal for heavily textured walls.

Pro Tip

Buy all your paint at once to ensure consistent color across the room. Batch mixing can vary slightly between purchases.

Standard Openings

Standard door~21 sq ft
Standard window~12 sq ft
Sliding door~40 sq ft
Large window~18 sq ft

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