calcs.homes
calcs.homes
Enter the tile area and pick the tile size that matches your trowel, and this thinset calculator estimates the 50-lb bags of mortar to buy.
Estimate only — an uneven substrate, back-buttering, and large-format tile all raise real coverage.
A 50-lb bag of modified thinset covers a coverage area that depends almost entirely on trowel notch size: a 3/16-inch V-notch for mosaics spreads thin and covers a lot, while a 1/2-inch square notch for large-format tile lays a thick bed and covers far less. We divide your tile area by the coverage for the trowel that matches your tile size and round up.
Real coverage drops when the substrate is out of flat and you have to build up low spots, and it drops again when large tile requires back-buttering, which effectively doubles the mortar under each piece. Treat the bag count as a floor, not a ceiling, and pick up one extra bag for a big job.
Roughly 90–95 sq ft with a 3/16-inch trowel, 60–70 sq ft with a 1/4-inch trowel, and 40–50 sq ft with a 1/2-inch trowel per 50-lb bag.
Yes — tile 15 inches or larger on any side should be set in a large-format / medium-bed mortar, which resists slumping in the thicker bed those tiles need.
Back-butter any large-format tile and any tile going on a wall or over an uneven floor. It fills voids and gets you to the 80–95% mortar contact that floors and wet areas require.