Home & DIY
Paint Calculator
Estimate the paint needed for a room from its size, openings and coats.
Paint Calculator
Paint needed
— gal
Paintable wall area—
Liters—
Assumes ~350 sq ft per gallon and deducts doors (~21 ft²) and windows (~15 ft²).
How much paint do I need?
Paint covers roughly 350 square feet per gallon. Work out the wall area (perimeter × height), subtract doors and windows, then multiply by the number of coats. This calculator does it all for you.
Buy a little extra for touch-ups and uneven surfaces.
Frequently asked questions
How much does a gallon of paint cover?
About 350–400 square feet per gallon for a single coat on a smooth surface.
Should I count the ceiling?
This calculator covers walls only. To paint the ceiling, add its area (length × width) separately.
How many coats should I apply?
Two coats are standard for good coverage. Going from a dark to a light color may need three.