Free Calculator
Paint Coverage Calculator
Enter your room dimensions and get the exact gallons of paint you need — no guesswork, no wasted cans.
How much paint do you need?
One gallon of interior paint covers approximately 350–400 square feet per coat. We use the conservative 350 sq ft estimate to make sure you don't run short — nothing's worse than an unfinished wall because you're a quarter gallon short.
The formula: Calculate the perimeter of the room (2 × length + 2 × width), multiply by the ceiling height to get total wall area. Subtract door area (~20 sq ft each) and window area (~15 sq ft each). Multiply by the number of coats. Divide by 350.
Do you need a primer coat? If you're painting over a dark colour or bare drywall, add an extra primer coat to your calculation. Primer coverage is similar to paint — about 300–350 sq ft per gallon.
Buying tip: For small jobs under one gallon, buy quarts instead — they're more cost-effective than paying for a full gallon you won't use. For large rooms, consider 5-gallon buckets for better value.
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