Total Area = Wall Width × Wall Height × Number of Walls
Paintable Area = Total - Windows/Doors
Gallons = (Paintable Area × Coats) / Coverage per Gallon
Get the right amount of paint for your project.
⚠Add 10% extra for waste, touch-ups, and future repairs. Different surfaces may need more paint.
Paint Coverage Guide
Interior Walls
350-400 sq ft per gallon per coat
Exterior Walls
300-350 sq ft per gallon per coat
Ceilings
350 sq ft per gallon per coat
Trim/Doors
400-450 sq ft per gallon
Teaching Example: Room with 4 walls, 12×9 ft each. Total = 432 sq ft. Minus 20 sq ft windows = 412 sq ft. 2 coats = 824 sq ft. At 350 sq ft/gal = 2.36 gallons.
Free online calculators and tools covering mathematics, unit conversion, text processing, and daily life. Accurate, fast, mobile-friendly, and completely free to use.