Paint Calculator — Free Online Paint Calculator

Estimate how many gallons of paint your room needs. 100% free, no signup.

Paint needed
0 gal
Paintable area0 ft²
Coats2
Coverage~350 ft²/gal

How much paint do I need?

One gallon of interior paint covers roughly 350 square feet. Multiply your wall perimeter by the ceiling height, subtract about 20 ft² per door and 15 ft² per window, multiply by the number of coats, then divide by 350.

Still choosing the color? Browse our designer paint color guides — the best whites, grays, and room-by-room picks with Sherwin-Williams and Benjamin Moore codes.

Redesign the whole room, not just the numbers

RoomGPT shows you the finished look on a photo of your space. Download free.

See how it works
Download RoomGPT on the App Store Get RoomGPT on Google Play

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Frequently asked questions

How many square feet does a gallon cover?

About 350 ft² per coat on smooth walls. Rough or porous surfaces and dark-to-light changes reduce coverage.

Do I need primer?

Use primer on new drywall, big color changes or stained areas. Many modern paints are paint-and-primer in one for repaints.

Not sure about the color?

Download RoomGPT free and preview wall colors and full redesigns on a photo of your actual room first.