How to use this paint calculator
Enter the requested values above and select Calculate. The result updates immediately on the page, so you can change one value and compare different scenarios without leaving the calculator.
Formula and method
Example
A 15×12 ft room with 8 ft walls has 432 sq ft of wall area before subtracting doors and windows.
What this calculator is useful for
Estimate gallons of wall paint from room dimensions, wall height, coats and paint coverage. It is designed for quick estimates and everyday problem solving. When a calculation affects a contract, tax filing, medical decision or other high-stakes situation, verify the result with the appropriate professional or authoritative source.
Frequently asked questions
What does the Paint Calculator calculate?
Estimate gallons of wall paint from room dimensions, wall height, coats and paint coverage.
How does the calculation work?
Wall area = 2(length + width) × height. Gallons = wall area × coats ÷ coverage.
Is this calculator free?
Yes. ERICH Calculators is free to use and no account is required.