How much area does a gallon of paint cover?

Most interior paints cover 350–400 sq ft per gallon on a smooth surface. Use 350 for a conservative estimate. Textured or porous surfaces need more.

Should I buy exactly what the calculator says?

Round up to the nearest half or full gallon for touch-ups. Leftover paint stores well sealed for up to 10 years.

Paint Calculator

Quick answer: Enter room size and number of coats to find out how many gallons of paint you need.

Enter your room dimensions, number of coats, and the number of doors and windows to calculate exactly how many gallons of paint you need. Accounts for 350 sq ft per gallon coverage (adjust to match your paint's label).

Last reviewed: April 2026Report an error

Room Length (ft)

Room Width (ft)

Ceiling Height (ft)

Coverage (sq ft/gallon)

Number of Coats

Doors

Windows

Include ceiling

Gallons Needed

2 gal

302 sq ft of wall area × 2 coat(s) = 604 sq ft total. You need 2 gallon(s) (8 quarts).

Wall Area

302 sq ft

Ceiling Area

0 sq ft

Gallons (rounded)

2 gal

Quarts

How to Use This Paint Calculator

1Enter room length, width, and ceiling height in feet.
2Enter the number of coats (typically 2 for walls).
3Enter the number of doors and windows to subtract from wall area.
4Toggle ceiling paint if you are painting the ceiling too.
5Read gallons needed, rounded up to the nearest half-gallon.

Frequently Asked Questions

: Most interior paints cover 350–400 sq ft per gallon on a smooth surface. Use 350 for a conservative estimate. Textured or porous surfaces need more.
: Round up to the nearest half or full gallon for touch-ups. Leftover paint stores well sealed for up to 10 years.

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