How it works
The method behind the number.
Estimate paintable area and the number of gallons to buy. This tool explains the calculation so you can adjust the assumptions to match your situation.
Your formula appears here after the calculator loads.
Home & build
Paint calculator
Estimate paintable area and the number of gallons to buy.
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Your result
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Enter your numbers to see the answer.
Paint calculator guide
What does this calculator help you figure out?
Estimate paintable area and the number of gallons to buy. This free online calculator is designed for people who need a quick, transparent estimate rather than a black-box answer. Enter room length, room width, wall height, doors, windows, review the assumptions, and adjust the values to match your project or situation.
How is the result calculated?
Paintable area = wall area minus openings; gallons = paintable area ÷ coverage per gallon.
Example and assumptions
For a useful first estimate, start with the sample values already shown in the calculator, then replace them with your own measurements or figures. Keep all dimensions in compatible units and round up where the result represents a quantity you must buy.
Results are planning estimates. Check the units, product coverage, carrier rules, or local rates before making a purchase or financial decision.
Common questions
Frequently asked questions
What does this paint calculator calculate?
Estimate paintable area and the number of gallons to buy. The page shows the result, a breakdown, and the formula used so you can check the calculation.
What information do I need?
You will need room length, room width, wall height, doors, windows. The labels and units beside each field show what the calculator expects.
How accurate is the result?
Results are planning estimates. Check the units, product coverage, carrier rules, or local rates before making a purchase or financial decision. Accuracy depends on the quality of the inputs and the assumptions used by the underlying formula.
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