Divide paintable area by coverage rate to find how many gallons and quarts you need.
Overview
Paint coverage depends on surface porosity, color change, and the product’s stated square feet per gallon. Under-buying forces mid-project store runs; over-buying ties up cash in unused cans.
Enter total wall (or ceiling) area and the coverage rate from the can. The calculator returns gallons and an equivalent quart count.
Subtract windows and doors from gross wall area before you calculate, and plan a second coat when covering dark colors.
Steps
Sum wall or ceiling square footage.
Remove window and door areas.
Use sq ft per gallon from the label.
Review gallons and quarts needed.
Double the result if you need two full coats.
Math
gallons = wallArea / coveragePerGallon; quarts = gallons × 4
Required volume equals area divided by coverage. Quarts are gallons times four.
Worked cases
400/350≈1.14 gal ≈ 4.6 qt
About 1.2 gallons for one coat.
1.14 × 2 ≈ 2.3 gal
About 2.3 gallons for two coats.
80/400=0.2 gal = 0.8 qt
About one quart for one coat.
Why use this
Questions