MeasureHaven

Walls & finishes

Paint & cans calculator

Estimate wall paint from room dimensions, openings, coats and label coverage, then round to whole cans.

Your project

ft
ft
ft
ft²
ft²/US gal
Use the label’s coverage for one coat. Default is approximately 350 ft² per US gallon.
US gal
%
Extra material for cuts, spillage or irregular edges. Adjust for your project.
Optional. Enter your supplier’s price; 0 leaves cost out.

YOUR ESTIMATE

Enter your measurements and select Calculate estimate.

Planning estimate only. Confirm the product’s coverage and your measurements before ordering.

How to use this estimate

Add the area of unpainted doors and windows and enter it once. Coverage is for one coat, so the calculator multiplies by the number of coats separately. Rough surfaces, strong color changes and porous substrates can need more paint than a smooth primed wall. Replace the sample rate with the label’s coverage for your paint.

The calculation

Wall area = 2 × (length + width) × height − openings. Paint = wall area × coats × allowance factor ÷ coverage.

A worked example

A 12 × 10 × 8 ft room has 352 ft² of walls. Subtract 40 ft² of openings: two coats at 350 ft² per US gallon plus 5% need 1.872 gallons, or 2 one-gallon cans.

Walls only: ceiling, trim, primer and doors are excluded. Gallons are US gallons, not imperial gallons.

Common questions

Is the ceiling included?

No. Calculate ceiling area as length × width and estimate it separately using the chosen product’s coverage and number of coats.

References & method

BEHR coverage guidance. See how we check calculations. Reference links provide context; no supplier endorses this site.