Enter your room size, number of coats, and paint coverage to estimate gallons to purchase, with doors and windows accounted for.
Four-wall area = 2 × (length + width) × room height. Subtract the area of large openings, add ceiling area if selected, then multiply by the number of coats. Divide by product coverage in square feet per gallon.
Learn about the underlying method: Sherwin-Williams paint calculator ↗
Note: This tool estimates quantities, not structural requirements, installation safety, code compliance, or product suitability.
Sherwin-Williams notes that a gallon typically covers about 350–400 sq ft, though product and surface conditions matter. This tool defaults to 350.
The result rounds to full one-gallon can equivalents for a simple purchasing estimate. Quarts and larger containers may produce different costs.
No. Primer, trim, extra colors, and separate ceiling products need their own coverage calculations.