Enter your room dimensions to estimate how much paint you need for walls. Adjust for doors, windows, coverage rate, and overage to get a planning estimate — verify before purchase.
Enter your project dimensions and click Calculate to see your estimate.
Typical materials for a paint project
Use your gallon estimate as a starting point. Verify coverage rates on product labels before purchase.
Our paint calculator estimates total gallons based on wall surface area, minus typical deductions for doors and windows.
Results are planning estimates based on typical assumptions. Verify quantities with product labels and your project layout before purchase. How we calculate
A 12×12 room with 8-foot ceilings has about 384 sq ft of wall area before deducting doors and windows. With two coats and standard coverage (375 sq ft per gallon), you typically need about 2 gallons. Use our paint calculator for your room dimensions.
Most interior walls need two coats for even color and durability. One coat may work for touch-ups or when covering a similar color. Dark-to-light color changes often need a primer plus two finish coats.
Yes. Most interior latex paints cover 350–400 sq ft per gallon per coat, but premium and textured paints may cover less. Check the label on your specific product and enter that number in the calculator.
Yes. Standard practice deducts about 20 sq ft per door and 15 sq ft per window. Our calculator applies these defaults so you do not over-order.
Add 10–15% overage for touch-ups, roller absorption, and uneven surfaces. The calculator includes a waste percentage and rounds recommended purchase up to whole gallons.
This tool estimates wall paint based on room perimeter and ceiling height. Ceiling area is not included. Add ceiling square footage separately if you plan to paint the ceiling.
Unopened latex paint lasts 2–10 years when stored properly. Opened cans last 1–2 years. Buying one extra gallon for touch-ups is still a good idea even if shelf life is limited.
The formula works for any flat wall surface, but exterior paint often has different coverage rates and may require more coats. Adjust coverage and coats to match your exterior product.
