What does this tool do?
Thin-set coverage is set by the trowel notch rather than the tile alone. This calculator uses typical coverage for common notches, scales it to the bag size and adds a waste allowance for back-buttering.
The Formula
Bags = ⌈Tile area × (1 + Waste ÷ 100) ÷ Coverage per bag⌉Frequently Asked Questions
What trowel size should I use?
Match the notch to the tile: 1/4 × 1/4 in for small tile, 1/4 × 3/8 in for 12 in tile and 1/2 × 1/2 in for large-format tile.
Why does coverage vary so much?
Notch depth, the tile back pattern and floor flatness decide how much adhesive actually contacts the tile.