Paint Calculator

Manual

Use Paint Calculator to estimate paint quantity from measured paintable area, coats, product coverage, an optional extra allowance, and the container size you plan to buy.

Choose a measurement mode

Interior room calculates wall area only. Individual walls and Exterior walls use repeatable width x height x quantity rows. Ceiling uses length x width x quantity. Known area accepts a net paintable area you already measured.

US and Metric units

US mode uses feet, square feet, coverage in square feet per US gallon, and gallons or quarts for container size. Metric uses meters, square meters, square meters per liter, and liters. Switching systems converts current values rather than resetting them.

Openings

Interior room, Individual walls, and Exterior walls can subtract measured doors, windows, or other openings. Opening area must remain smaller than gross wall area. Ceiling and Known area do not use opening deductions.

Coats and coverage

Coats must be a whole number from 1 through 20. Coverage is per coat and must be greater than zero. The 350 square feet per gallon default is only a planning starting point; use the actual paint label when available.

Extra / touch-up allowance

The optional allowance accepts 0% through 100% and starts at 0%. It is shown separately from the base paint need.

Container size and purchase rounding

Enter the container size you expect to buy. The calculator keeps the exact planned need unrounded, then rounds only the container count upward. Retail package availability depends on the product and seller.

Changing an input

After a valid calculation, changing any calculation input marks Results as Needs update and disables Copy, CSV, and Print until you calculate again. A validation error does not silently replace the previous valid result.

Copy, CSV, and Print / Save PDF

Copy and CSV use the same active result model shown on the page. Print / Save PDF keeps the project inputs, assumptions, and result breakdown while hiding ads, product recommendations, navigation, and unrelated supporting content.

Validation limits

Required dimensions must be positive plain decimals. Exponent notation, non-finite values, invalid units, more than 100 wall rows or 100 opening rows, and quantities outside 1 through 1,000,000 are rejected. Optional row labels support up to 80 Unicode characters.