Paint Calculator
Enter your wall area and number of coats to estimate gallons of paint needed, based on standard coverage rates.
Last updated: August 30, 2026
Frequently asked questions
How much paint covers 400 sq ft?
At standard 350 sq ft per gallon coverage, one coat over 400 sq ft needs about 1.14 gallons - round up to be safe.
Should I subtract doors and windows from wall area?
For a rough estimate, no - most painters skip this since the extra paint from not subtracting covers trim work and touch-ups. For large window/door areas, subtracting them can save you from buying more than you need.
How much extra paint should I buy for touch-ups later?
Buy a little more than the calculated amount - rounding up to the next full gallon or quart covers touch-ups and accounts for uneven coverage on textured surfaces.
How many coats of paint does this calculator assume?
This calculator estimates paint needed for two coats, which is standard for most interior and exterior jobs, especially when changing colors significantly. If you're covering a similar color with a single coat, you can roughly halve the estimated paint quantity.
Is a 'paint coverage estimator' the same as this tool?
Yes - enter your wall area, number of coats, and coverage rate per gallon above to get the same estimate.