Paint Calculator
Calculate gallons of paint needed for any room, including doors and windows.
How to calculate how much paint you need
Measure each wall's length and height. Entering the room length and width works too — the calculator treats all four walls.
Enter the ceiling height, number of doors, and number of windows. Doors subtract about 20 sq ft each; windows subtract about 15 sq ft.
Choose the number of coats. Fresh drywall or drastic color changes usually need two. Touch-ups and same-color repaints often need just one.
Read the gallons needed and round up to the next full gallon. A little leftover is useful for future touch-ups.
Common uses
- Painting a bedroom, living room, or kitchen before moving in
- Estimating paint for a whole-house interior refresh
- Budgeting material costs for a rental property turnover
Frequently asked questions
How much area does a gallon of paint cover?
Do I need a primer before painting?
How much paint do I need for a 12×12 room?
Not sure whether to DIY this project?
Read our project-by-project guide on when to hire a contractor vs. do it yourself.
About this calculator
Enter room dimensions, ceiling height, number of doors and windows, and number of coats to get the exact gallons of paint you need. Accounts for standard door and window sizes.
All results are estimates. Verify quantities with your local supplier and confirm measurements before purchasing materials. Requirements vary by region and project type.
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