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How much paint do I need for a room?

Enter the room dimensions and openings to get the gallons to buy — then see the walls in 3D. Defaults assume one door and one window; adjust to your room.

Length
ft
in
Width
ft
in
Wall height
ft
in

Result

Enter your measurements to see the result

How is this calculated?

Wall area = perimeter × height = 2 × (length + width) × height. From that we subtract the openings you won't paint — 21 ft² per door (a standard 3′×7′) and 15 ft² per window (about 3′×5′).

Multiply the paintable area by the number of coats, divide by 350 ft² — the area one gallon covers per coat — and round up to whole gallons. Coverage varies by paint and surface; bare, patched, or dark walls may need a primer coat first.

Formula sources: Manufacturer coverage data — ~350 ft² per gallon, one coat, Standard door (3′×7′) and window (3′×5′) sizes

Estimates only. Always verify with your supplier and local code requirements.