Room size
Coats
Typical latex is about 350 sq ft per gallon, per coat. Check the can.
Buy
- Paintable sq ft
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- Gallons
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- Cans to buy
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- Est. cost
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Enter length, width, and height.
This is an estimate, not a spec and not a price quote. Coverage varies by product, color, sheen, and surface. Always check the number printed on the can. Quart pricing here is one-fourth of a gallon; store quarts often cost more per ounce.
How the paint is counted
Wall area is the room’s perimeter times height: 2 × (length + width) × height. Each door knocks off 20 square feet (a typical 3 ft × 6 ft 8 in interior door). Each window knocks off 15 square feet. The ceiling, if you turn it on, is length × width. Openings cannot take the walls below zero.
Paintable area is that net square footage times coats (default 2). Gallons are paintable area ÷ coverage (default 350 sq ft/gal). We then round up to 1 gallon and 1 quart cans so a leftover still becomes another can.
wall_sq_ft = 2 × (L + W) × H net_walls = max(0, wall_sq_ft − doors×20 − windows×15) one_coat = net_walls + (ceiling ? L×W : 0) paintable = one_coat × coats exact_gal = paintable ÷ coverage cans = ceil(exact_gal × 4) quarts, then 4 qt = 1 gal
Example: 10 ft × 10 ft × 8 ft, 1 door, 1 window, 2 coats, 350 sq ft/gal, walls only. Walls 320 − 20 − 15 = 285 sq ft. Two coats = 570. 570 ÷ 350 = 1.63 gal → 1 gallon + 3 quarts (or 2 gallons).
FAQ
How much paint do I need?
Measure the room, subtract doors and windows, multiply by coats, divide by the coverage on the can. This page does that and rounds up to cans.
How much paint for a 10×10 room?
At 8 ft high, 1 door, 1 window, two coats, 350 sq ft/gal: about 1.63 gallons. Buy 1 gallon + 3 quarts, or 2 gallons. Change the height or openings above.
How many square feet does a gallon of paint cover?
About 350 square feet per coat for typical latex. Primer, dark colors, and rough walls cover less. Check the can.
Do I need two coats?
Two is the usual interior finish, so that is the default. One coat is a primer or a touch-up. Three shows up on a deep color change.