Gallons per Square Foot Calculator
Work out how many gallons of a liquid you need to cover an area, based on the coverage rate of the product.
What this calculator does
This tool converts a product’s coverage rate (square feet per gallon, usually printed on the label of paint, sealant, stain, or waterproofing coatings) into the total number of gallons you need to buy for your project.
The formula
Gallons needed = area to cover ÷ coverage rate per gallon, multiplied by the number of coats you plan to apply. For example, covering 500 square feet with a product rated at 350 square feet per gallon takes about 1.43 gallons per coat.
Coverage rates vary by surface texture, porosity, and application method, so always check the manufacturer’s label and round up to the nearest full container. This calculator is for general planning purposes.