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Paint calculator
Estimate the wall surface to paint, subtract openings, apply the number of coats, and add a waste allowance using the coverage from your paint can.
What this tool does
Enter your room dimensions and the coverage printed on your paint can to get a practical paint quantity estimate.
Calculator
Enter your room details.
Use the coverage printed on your paint can. The default is only a starting point.
Calculation result
Your result
Enter details to see the estimate.
The result separates wall area, coverage, waste allowance, and the rounded quantity to consider buying.
How it works
The estimate calculates the four wall surfaces, subtracts doors and windows, multiplies the remaining area by your coats, divides by your coverage, and then adds your waste allowance.
Assumptions
- The room is treated as four rectangular walls with no sloped ceilings.
- Door and window openings are subtracted once from the wall surface.
- Coverage is supplied by you and should match the paint product and surface.
Limitations
- The estimate does not account for ceilings, trim, textured surfaces, primer, or separate colors.
- Actual purchasing may depend on available container sizes and the condition of the surface.
- Paint labels and local product guidance should take priority over this estimate.
Good to know
Frequently asked questions
What coverage should I enter?
Use the coverage printed on your paint can or product data sheet. Coverage varies by product, surface, application method, and color.
Why add waste?
Waste allows for spills, roller or brush loading, touch-ups, uneven surfaces, and small measuring differences. You control the percentage in the calculator.
Should I paint the ceiling?
Not in this estimate. Add a separate ceiling calculation or use a calculator designed for ceilings if you need that quantity.
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