Room Paint Coverage Calculator
Calculate exactly how much paint you need for a room.
Enter dimensions, number of coats, and ceiling preference to get gallons needed and estimated cost.
Paint Needed
Paint Coverage Formula
Wall Area = 2 × (Length + Width) × Height − Door and Window Area Coverage per gallon ≈ 350 sq ft (standard interior paint, one coat)
Gallons Needed = (Wall Area × Number of Coats) ÷ 350
Add 10% waste for edging, touch-ups, and roller absorption.
Standard door area: ~20 sq ft | Standard window: ~15 sq ft