Paint Calculator
Enter the wall area, number of coats and coverage printed on your paint can to estimate how many gallons of paint the project requires.
Start with the essentials
Enter the room size first. Doors, windows, coats and product coverage can be refined below.
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Check the method or common questions
Method, formula & assumptions
Interior material estimating
Formula: Wall area is calculated from room perimeter and wall height. Paint then multiplies that area by the number of coats and divides by your entered coverage rate; drywall converts wall area into sheet quantities.
Worked example: Example: a 10 × 12 ft room with 8 ft walls has 352 ft² of gross wall area before multiplying by paint coats.
Before you buy: Doors, windows, texture, porosity and application method affect actual coverage. Using gross wall area is a simple way to preserve a practical allowance on many projects.
Paint Calculator FAQ
Should I subtract doors and windows?
For a quick estimate, leaving small openings in the gross area can provide useful extra material. Large openings can be subtracted for a tighter estimate.
Why enter paint coverage myself?
Coverage varies by paint and surface. The number printed by the manufacturer is more useful than assuming one universal rate.
Continue your Paint, Drywall & Wallpaper project
Use the Paint, Drywall & Wallpaper planning hub for related calculators and quick-reference guides.
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