Project Parameters
Total perimeter of all exterior painted walls.
Ground to roof eaves (approx. 9-10 ft per story).
Sum of door and window areas (average window = 15 sq ft).
Instant Estimate
Trim & Fascia Paint
Covers window frames, eaves, corner boards, and fascia.
Exterior Primer (if raw or color change)
Recommended for bare wood, masonry, or severe color transitions.
Net Wall Surface Area
Coverage Rate Used
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Guide
How to calculate exterior paint gallons
Exterior paint calculations require measuring net wall area, choosing coverage rates based on wall texture (stucco and masonry absorb 40% more paint than smooth lap siding), and planning for 2 full coats.
Calculate Net Siding Area
Multiply total building perimeter by wall height, and subtract window and door openings.
Adjust for Surface Porosity
Smooth siding covers 350 sq ft per gallon; textured stucco covers ~250 sq ft; rough brick or shake covers ~180 sq ft.
Multiply by Coats
Always apply 2 coats on exterior surfaces for UV resistance and weather protection.
Add Trim Allowance
Estimate trim, fascia boards, gutters, and door frames as 10% to 15% of the body paint quantity.
Mathematics
Formulas used
Net Wall Area
(Perimeter × Wall Height) − Door & Window AreasExterior square footage requiring paint coverage.
Gallons Required
(Net Area × Number of Coats) / Spread RateDivide total painted square footage by manufacturer coverage per gallon.
Answers & FAQ
Frequently asked questions
How many gallons of paint to paint a 2,000 sq ft house?▼
A 2,000 sq ft single-story home typically has 1,500–1,800 sq ft of exterior wall area. For 2 coats on smooth siding, you will need 10 to 12 gallons of body paint and 2 gallons of trim paint.
Is 1 coat of exterior paint enough?▼
One coat is only sufficient if you are applying the exact same color over a well-maintained surface. For color changes, weathered wood, or raw surfaces, 2 coats are mandatory for warranty coverage and longevity.
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