How this calc works

Thinset coverage depends on two things: your tile size and your trowel notch. Bigger tile needs a bigger notch, a bigger notch lays down more mortar per square foot, and more mortar per square foot means fewer square feet per bag. This calc works from your area and tile size to estimate bags so you are not guessing off the label.

A rough field rule: a 50-lb bag covers about 95 square feet of small tile with a 1/4-inch notch, but only 40-50 square feet of large-format tile with a 1/2-inch notch. The label number on the bag almost always assumes the small-tile case.

Common mistakes

The most expensive mistake is buying thinset by the label number for a large-format tile. You can run out at half the square footage you planned, and a half-set floor that skins over is a redo, not a pause.

The second is mixing more than you can lay before it stiffens. Thinset has a working time; mix to your pace, not the whole bag at once, or you throw away mortar that set in the bucket.

RELATED FORMULAS