Painting Calculators
Turn wall area into gallons, not guesswork.
Paint stores will happily sell you extra gallons. Coverage on the can assumes a smooth, sealed surface and a specific film thickness. This calculator estimates paintable area from room dimensions (or a direct square-footage entry), subtracts openings, applies coats, and divides by a coverage rate you can match to your product. It does not account for heavy texture, color changes from dark to light, or primer as a separate product unless you add a coat. Use it to buy once, then keep a labeled quart for touch-ups.
Calculators
How to measure
Measure each wall’s width and height, or enter perimeter × ceiling height. Subtract standard doors (~20 sq ft) and windows (~15 sq ft) or use your own measurements. Ceilings are length × width. If walls are rough or you are covering a dark color, lower the coverage rate rather than trusting the marketing number on the can.
Related categories
FAQ
- How much area does a gallon cover?
- Many interior latex paints claim about 350–400 square feet per gallon per coat on smooth drywall. Porous new drywall, masonry, and deep color changes need more paint. Use the coverage printed for your specific product.
- Should I buy primer as extra gallons in this tool?
- If you need a dedicated primer, add it as an extra coat or run the calculator again for primer only. Tinted paint-and-primer products are still two coats of the same gallon count, not a substitute for sealing raw drywall.