Home Improvement
Paint calculator
Buying paint is easier when you know the wall area instead of guessing by room size. Enter your room dimensions, doors, windows, and number of coats to estimate paintable square footage and gallons needed. The formula uses a common coverage range of about 350 to 400 square feet per gallon and subtracts standard openings. Use the result to plan your shopping list, then check the label on your chosen paint because coverage varies with color, surface, and application method.
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Paint Calculator
Estimate gallons of paint for a room, including doors, windows, and coats.
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Painter's tapeYour paint math is done — clean edges are next.Paid link · Check current price ↗As an Amazon Associate I earn from qualifying purchases.The math, plainly
How it works
- 01
Wall area is the room perimeter multiplied by wall height.
- 02
This estimate subtracts 21 square feet per door and 12 square feet per window.
- 03
Paint needed is paintable area × coats ÷ 375 square feet per gallon, rounded up when buying whole gallons.
Try a real scenario
12 × 10 room
Inputs8 ft walls, 1 door, 2 windows, 2 coats
ResultAbout 307 sq ft of paintable area and 1.6 gallons, so buy 2 gallons.
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