Free tool
Paint calculator
Estimate gallons for a room's walls. Set the coverage from the paint can label.
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How it works
How it works
Wall area is 2 x (length + width) x height. The calculator subtracts about 21 square feet per door and 15 per window, multiplies by coats and divides by the coverage per gallon. Coverage is printed on the can, and 350 is a common figure.
Example: a 12 by 10 foot room with 8 foot ceilings has 2 x (12 + 10) x 8 = 352 square feet of wall. One door and two windows remove about 51 square feet, leaving 301. Two coats at 350 square feet per gallon need about 1.72 gallons, so buy 2. Dark colors, rough walls and fresh drywall can need more.
FAQ
About this calculator
Does this include the ceiling?
No, only walls. Use the square footage calculator for the ceiling.
Do I need primer?
It depends on the surface and the color change. Check the paint's instructions.
Why round up?
Paint comes by the gallon and a little extra helps with touch-ups.
Is anything saved?
No. The math runs in your browser and nothing you enter is sent to us.
Read the guide: How Much Paint Do I Need for a Room?. See all free tools. More free tools: Aspect ratio calculator, Recipe scaler, Mix ratio calculator, or see all free tools.
General information, not tax or legal advice. How we write and check our tools.