Paint Calculator
Find out exactly how much paint you need for any room.
Wall dimensions
Subtract openings
How the Paint Calculator Works
The calculator finds your wall perimeter, multiplies by ceiling height to get total wall area, then subtracts an average for each door (21 ft² / 1.95 m²) and window (15 ft² / 1.4 m²). It multiplies by the number of coats and divides by typical coverage: 350 ft² per gallon or 10 m² per liter.
Tips for Accurate Estimates
Buy slightly more than the calculator suggests so all your paint comes from the same batch. Primer goes further than finish coats — usually one coat is enough on already-painted walls. Dark colors over light walls usually need an extra coat.
FAQ
How much paint per gallon?
One US gallon covers about 350 square feet with one coat of standard latex paint. One liter covers about 10 square meters.
Do I need primer?
If you're painting bare drywall, going from dark to light, or covering stains — yes. If you're refreshing an existing painted wall in a similar color, you can usually skip it.
How many coats?
Two coats is standard for most colors. Three may be needed for bold reds, yellows, or going from dark to white.
Does this include the ceiling?
No — only walls. Calculate ceilings separately as length × width.
Is my data stored?
No. The tool runs entirely in your browser.
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