Paint Calculator
Calculate how many gallons of paint you need from room dimensions. Enter room size, number of coats, doors, and windows for an accurate estimate.
Frequently Asked Questions
How is paint coverage calculated?
Standard paint covers approximately 350 square feet per gallon. The calculator computes total wall area (2 × (width + length) × height), subtracts 20 sq ft per door and 15 sq ft per window, then multiplies by the number of coats and divides by 350.
Why add 10% extra paint?
Adding a 10% buffer accounts for touch-ups, spills, uneven absorption, and future repairs. It is generally better to have a little paint left over than to run out mid-job and risk a colour mismatch when buying more.
How many coats of paint do I need?
Most walls need 2 coats for a uniform finish. Use 1 coat if you are repainting with the same or a similar colour. Use 3 coats when covering a dark colour with a lighter one, painting raw drywall, or using a primer coat separately.