Paint Coverage Calculator: How Much Paint?
Running out of paint mid-wall is a rite of passage nobody wants. And guessing wrong in the other direction means a $60 gallon gathering dust in the garage for a decade. The math isn't hard — it's just fiddly: wall area minus doors and windows, times coats, divided by coverage.
This free calculator does it for you. Enter your total wall area, doors, and windows, pick one or two coats, and get the exact gallons (and quarts) to buy — with a 10% bump option for textured or porous walls. Below your result you'll find top-rated paints and supplies on Amazon.
How Much Paint Do You Need?
Running out mid-wall is the worst. Enter your wall area and we’ll calculate exactly how many gallons to buy — including doors, windows, and coats.
Paint to buy
Based on the standard coverage of 350 sq ft per gallon, minus 20 sq ft per door and 15 sq ft per window. Textured or porous walls drink about 10% more paint. Always round up: leftover paint is cheap insurance for touch-ups.
As an Amazon Associate we earn from qualifying purchases.
Frequently asked questions
How many square feet does a gallon of paint cover?
The industry standard is about 350 square feet per gallon for interior latex paint on smooth walls. Real-world coverage drops on textured, brick, or unprimed surfaces.
Should I do one coat or two?
Two coats, almost always. The first coat seals and evens out the surface; the second delivers the true, rich color.
How do I measure wall area for paint?
Measure each wall’s width and height in feet, multiply them, and add all walls together. Then subtract about 20 sq ft per door and 15 per window — our calculator does that for you.
Is it better to buy extra paint?
Yes — always round up. Touch-ups are inevitable, and paint colors vary slightly between batches.
What’s the difference between a gallon and a quart?
A gallon is 4 quarts. Gallons are economical for whole rooms; quarts are perfect for accent walls and small bathrooms.