Paint Calculator
Estimate paint gallons from area, coats and real product coverage.
Enter your project details
Each dimension can use its own unit—for example feet for length and inches for thickness. Package counts are rounded up.
Formula and calculation steps
Quantity = adjusted area ÷ product coverage; packages are rounded up.- Start with 120 ft² after openings.
- Add 10% allowance.
- Apply selected product coverage and round up.
Worked example
For two coats, both coats are included in the required coverage before gallons are rounded up.
How to use this calculator
- Enter paintable area.
- Set coats and the coverage on the paint can.
- Read gallons rounded up for purchase.
Example: For two coats, both coats are included in the required coverage before gallons are rounded up.
Questions about this calculator
Does coverage include two coats?
Enter the number of coats; required coverage multiplies area by coats before gallons are calculated.
Should I paint over primer separately?
If primer is a separate product, estimate it as its own coat with its own coverage rate.
Can I use mixed units?
Yes. Choose feet, inches, metres or centimetres and the calculator converts each input before calculating.
Is this a final material order?
No. Confirm drawings, product coverage, local code and site conditions before buying or building.
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<iframe src="https://www.buildcalclab.com/embed/paint-calculator/?theme=light" width="100%" height="640" title="BuildWise calculator" style="border:0;max-width:720px"></iframe>Assumptions and references
Results are estimates based on the dimensions and values you enter. Verify final quantities, manufacturer coverage and site-specific requirements before ordering.
Last reviewed: July 2026 · Read our calculation methodology