Paint Calculator for a House Exterior
Estimate gallons of exterior paint for siding and trim.
This free paint calculator estimates gallons based on the room’s length, width, ceiling height, number of doors and windows, and number of coats. It calculates the paintable wall area, divides it by a coverage rate of 350 ft² per gallon, and shows how much paint to buy.
Gallons
1.81
Buy the next whole gallon
Paintable area
316 ft²
Total wall area
352 ft²
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How does the paint calculator work?
Wall area is the room perimeter × ceiling height. Subtract roughly 21 ft² per door and 15 ft² per average window, then multiply by the number of coats and divide by 350 ft²/gallon.
Formula: gallons = ((2(L+W) × H − doors×21 − windows×15) × coats) ÷ 350
What else do people ask about this calculator?
How many gallons of paint for a 2000 sq ft house exterior?
A 2,000 sq ft two-story house has roughly 1,600 sq ft of exterior wall. That's about 5 gallons for one coat or 10 gallons for two coats on smooth siding. Rough or textured siding can take 30–40% more.
Do I need to prime bare siding?
Yes. Bare wood, new fiber cement or spot-repaired areas need a dedicated exterior primer. Skipping primer voids most exterior paint warranties.
How much paint do I need for a 12×12 room?
A 12×12 room with 8 ft ceilings, 1 door and 1 window needs about 2 gallons for two coats.
How much does a gallon of paint cover?
About 350 ft² per gallon on smooth interior walls. Textured or porous surfaces reduce coverage to 250–300 ft².
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Where can I learn more about these materials?
Weights, coverage, types and buying tips for the materials this calculator estimates.
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