Paint Calculator Paint Calculator Estimate the amount of paint needed for your walls. Room Dimensions (Feet) Total Length of Walls: Measure all walls you plan to paint and add their lengths together. Wall Height: Areas Not to Paint (Doors, Windows, etc.) Number of Doors: Standard door area subtraction: ~21 sq ft per door. Number of Windows: Standard window area subtraction: ~15 sq ft per window. Other Deductions (sq ft): Enter total square footage of any other large areas not being painted (fireplaces, large openings, etc.). Paint & Coverage Number of Coats: Paint Coverage (sq ft per gallon): Check the paint can; typically 250-400 sq ft per gallon. Calculate Paint Needed
