Stucco Calculator

As a planning average, an 80 lb bag of three-coat base stucco covers about 25 square feet for the scratch and brown coats combined, while an 80 lb bag of finish coat covers about 70 square feet because it goes on much thinner. A one-coat base bag covers roughly 45 square feet.

A traditional three-coat system applies a scratch coat, a brown coat, and a finish coat over lath, so it uses more base material. A one-coat (or two-coat) system uses a single fiber-reinforced base coat plus the finish, so a bag of base stretches further and you need fewer base bags.

Yes. Enter the total square footage of doors, windows, and other openings so the tool works from the net area you actually cover. On a wall with large openings this can noticeably reduce the number of bags.

You cannot buy a fraction of a bag, and running short mid-job means an extra trip and a possible color or batch mismatch on the finish coat. Rounding up with a waste allowance keeps a small buffer on hand.

A 10 percent allowance is a reasonable default for typical walls. Increase it for rough or highly textured substrates, lots of corners, or an inexperienced crew, since spillage and rework consume more mix.