Paint Calculator

1. Enter room dimensions. Measure your room length, width, and ceiling height in feet. A standard bedroom is about 12 ft × 14 ft with 8 ft ceilings. The calculator uses the wall perimeter times the ceiling height to find total wall area.
2. Set the number of coats. Most paint jobs need 2 coats for solid coverage. Going over a dark color or painting bare drywall often requires 3 coats. One coat is only realistic with a paint-and-primer combo on a similar color.
3. Adjust coverage per gallon. The default 400 sq ft per gallon is typical for standard latex wall paint. Drop this to 300 if you are painting rough or heavily textured walls, or raise it to 450 for premium self-priming paints.
4. Read the results. The calculator shows gallons rounded up to the nearest whole gallon, quarts for smaller purchases, and an estimated cost range based on $30 to $60 per gallon, which covers budget to mid-range interior paints.

Example: a 14 ft × 12 ft room with 8 ft ceilings has a gross wall area of 416 sq ft. After deducting one door and two windows (51 sq ft), the net area is 365 sq ft. Two coats equals 730 sq ft total, needing 2 gallons at 400 sq ft coverage. Cost estimate: $60 to $120 for paint only, not including primer, brushes, or rollers.

The paint calculator uses a straightforward area formula. Ceilings are not included by default since ceiling paint is purchased separately, typically at a different coverage rate.

Always round gallons up to the nearest whole number when purchasing. Leftover paint stores well for touch-ups. A quart covers roughly 100 sq ft with one coat, so a single accent wall or small room may only need a quart rather than a full gallon.