One standard gallon of paint covers approximately 350 to 400 square feet of smooth wall surface per coat. Textured drywall or unprimed masonry reduces coverage to ~250-300 sq ft per gallon.
Paint Calculator
Estimate total paint gallons and primer needed for walls and ceilings minus windows & doors.
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Total Paint Gallons Needed
📐 Mathematical Formula & Standard
Gross Wall Sq Ft = 2 × (Length ft + Width ft) × Height ft
Net Sq Ft = Gross Sq Ft - ((Doors × 21) + (Windows × 15))
Gallons = Ceiling((Net Sq Ft × Coats) ÷ 350 sq ft/gal)
Net Sq Ft = Gross Sq Ft - ((Doors × 21) + (Windows × 15))
Gallons = Ceiling((Net Sq Ft × Coats) ÷ 350 sq ft/gal)
📖 Comprehensive Guide & Pro Estimating Tips
❓ Frequently Asked Questions
How many square feet does 1 gallon of paint cover? ▼
One gallon covers approximately 350 to 400 square feet per coat on smooth primed drywall.
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