# Paint quantity calculator

Canonical: https://colorswatchlab.com/tools/how-much-paint/
Author: Color Swatch Lab Editorial Team

Wall area is the perimeter times the wall height. Doors and windows are subtracted only at the areas you enter. Multiply by coats, then divide by coverage. One US gallon is 4 quarts. The buy line rounds up to the next whole quart.

Coverage starts at 350 square feet per gallon, the low end of a published range, and you can replace it:

- Sherwin-Williams SuperPaint Interior Latex Semi-Gloss A88 lists 350 to 400 square feet per gallon at 4 mils wet and 1.5 mils dry. Sheet marked 8/2026: https://www.sherwin-williams.com/document/PDS/en/035777051504/
- PPG Ultra-Hide Zero Interior lists 350 to 400 square feet per gallon on primed, smooth, nonporous surfaces. PDF marked 11/2017: https://buyat.ppg.com/rep_pafpainttools_files/PPG%20Ultra-Hide/TDB/1600-0100.pdf

The 12 by 12 by 8 foot example, with one door at 20 square feet and two windows at 15 square feet each, is the worked example from the quantity guide. Those opening areas are editorial allowances, not manufacturer measurements. Two coats in that example is the guide's example. The A88 application tips say priming and two coats at the recommended film thickness can help when hiding a previous coating or painting new drywall. That is not a rule for every can.

No price is shown unless you type a price per gallon. This site does not publish paint prices. Primer is not estimated. Sherwin-Williams' paint calculator FAQ says a gallon of primer covers about 200 to 300 square feet.

Dry to the touch is not ready to wash. The cure-time guide uses product-sheet intervals and the 2026 dates USPS and Amazon Shipping publish. It does not add a sale or an order deadline.