Paint Coverage Calculator
Find out exactly how many gallons and quarts to buy for a wall or an accent wall, accounting for doors, windows, and multiple coats.
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Why paint math matters
Buying too little paint means a mid-project store run and the risk of a slightly different batch tint; buying too much wastes money on a can that sits in the garage. The fix is simple arithmetic: multiply the wall’s width by its height for the gross area, subtract the doors and windows you won’t paint, multiply by the number of coats you plan to apply, and divide by the paint’s spread rate.
An accent wall is usually just one wall of a room, so measure it on its own rather than using a whole-room total. If you’re unsure of the spread rate, check the can’s label — textured walls, very porous drywall, and dramatic color changes all reduce real-world coverage below the printed number.
Frequently Asked Questions
How much wall does one gallon of paint cover?
Most interior wall paints cover 350–400 square feet per gallon in a single coat, though the exact figure is printed on the can. This calculator defaults to 350 sq ft/gallon, but you can enter your product's actual spread rate for a more precise number.
Why does the calculator subtract doors and windows?
A standard interior door opening removes about 20 square feet of wall you don't need to paint, and a standard window removes about 15 square feet. Subtracting them from the gross wall area gives a more realistic paint quantity instead of over-buying.
How many coats should I plan for?
Two coats is standard for a durable, even finish, especially over a different existing color or bare drywall. A single coat can work for a fresh coat of the same color in good condition, and a dramatic color change (light to dark, or vice versa) sometimes needs a tinted primer plus two topcoats.
Why does the tool round up to the nearest quart instead of a decimal gallon?
Paint is sold in quarts and gallons, not arbitrary fractions, so the calculator rounds your exact requirement up to the nearest quart (a quarter of a gallon) — the smallest unit you can actually buy at the store.
Educational estimate only. Actual coverage varies with wall texture, porosity, and paint brand — always check the can label and buy a little extra for touch-ups.