Home & Garden
Paint Calculator
Calculate how many gallons or liters of paint you need for a room based on its dimensions and number of coats.
You'll need about
3 gallons
(2.29 gallons exactly)
Most standard paint covers about 350–400 sq ft per gallon. Subtract large door/window areas from your wall area for a more precise estimate.
How the Paint Calculator works
Enter your wall area, number of coats, and your paint's coverage rate (found on the can). The calculator divides total area by coverage to estimate how many gallons you'll need.
Frequently asked questions
Should I subtract doors and windows?
For a more precise estimate, yes — subtract the area of large doors and windows from your total wall area before calculating.
How many coats do most walls need?
Two coats is standard for most interior walls, especially with a color change or over a darker existing color.
Guides that cover this
Planning a Home Project Without GuessworkSquare footage, paint, energy costs, and moving — the numbers behind common home and household decisions.How Much Paint a Room Actually Needs, With a Worked ExampleA worked example calculating the paint quantity needed for a room, accounting for wall area, coverage rate, and doors and windows.Why You Ran Out of Paint Partway Through a RoomThe common reasons an estimated paint quantity falls short of what a room actually needs.One Coat vs. Two Coats: Why the Paint Quantity Roughly DoublesWhy two coats of paint are standard for most projects, and why the quantity needed doesn't simply stay flat between one and two coats.How to Use the Paint CalculatorA quick walkthrough of finding out how much paint a room actually needs.Paint Calculator: How It Works and How to Use ItA quick guide to the paint calculator — what it calculates, how the math works, and tips for getting an accurate result.