How to use the Paint Coverage Calculator
Estimate paint gallons from surface area, number of coats, product coverage, and waste allowance. Enter the requested values, review their units, and select Calculate. The result panel shows both the answer and the substituted steps.
The formula
gallons = area × coats × (1 + waste) ÷ coverage
Frequently asked questions
Should doors and windows be subtracted?
Yes, subtract significant unpainted openings when you need a tighter estimate.
Why does actual coverage vary?
Surface texture, porosity, application method, color change, and product formulation all affect coverage.
Important notes
Results are estimates based on the values supplied and the formula shown. Round only at the end of a calculation, and verify safety-critical, medical, financial, or construction decisions with an appropriate professional.