Paint Coverage Calculator
Estimate how much paint to buy from wall area, coats, and openings. Rounds up to the nearest quart so you do not run short.
What you get
A net wall area after subtracting openings, total square footage for the number of coats, and a purchase quantity rounded up to the nearest quarter gallon. It uses a common coverage estimate of 350 square feet per gallon.
How to use it
Measure each wall as length times height, then add the walls together. Subtract about 20 square feet per door or window. Choose one, two, or three coats. Buy the rounded-up amount and keep the receipt; unopened paint is easier to return than a second trip.
One example
A room with 400 square feet of wall, two doors or windows, and two coats: 400 minus 40 leaves 360 square feet, times two coats is 720 square feet. At 350 square feet per gallon that is 2.06 gallons, so the tool tells you to buy 2.25 gallons.
Common questions
Does this include the ceiling and trim?
No. Measure the ceiling separately and use a different product for trim.
Do I need primer?
Add a primer coat when painting over a dark color, bare drywall, or patched walls. The calculator covers topcoats only.
What if my paint says a different coverage?
Use the number on the can. Coverage varies with texture, color, and application method.
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