Paint Calculator
Estimate interior wall paint from room perimeter, wall height, door and window deductions, number of coats and adjustable gallon coverage.
Switching systems clears entered values and restores any labeled editable examples in the new units. Individual dimension unit changes convert the entered length.
About the Paint Calculator
For a rectangular room, wall area is 2 × (length + width) × height. Enter the combined area of doors and windows to subtract them before applying coats. This is wall area only: ceilings and trim require separate estimates. Use the Square Footage Calculator for a ceiling or unusual surface.
The default assumes two coats and 350 square feet per US gallon per coat. Adjust coverage to your paint label, since texture, primer, color changes and application method affect yield. Results include US gallons and liters using 1 US gallon = 3.785411784 liters; the whole-gallon can count rounds gallons up and does not imply that paint is only sold in gallon containers.
Measure openings in square feet in imperial mode or square meters in metric mode. For a separate area estimate, use the Square Footage Calculator to measure the surface before planning paint. For covering walls with paper instead, use the Wallpaper Calculator to plan rolls and pattern allowance.
Frequently asked questions
Does this include ceiling paint?
No. It estimates the four rectangular walls. Calculate a ceiling separately using its length times width.
Why is coverage set to 350 square feet per gallon?
It is a common planning example, not a paint guarantee. Use the actual product's labeled coverage for better estimates.
Are door and window areas subtracted before coats?
Yes. The combined opening area is subtracted from one coat's wall area, then multiplied by the number of coats.
Take this calculation further
Browse the other calculators collection for more tools in this subject.
For a related calculation, use Wallpaper Calculator to estimate wallpaper rolls from room wall area, openings, roll dimensions and pattern waste in imperial or metric units. Alternatively, use Flooring Calculator to estimate room area, waste allowance and flooring boxes in imperial or metric units for tile, laminate or hardwood.