Thinset Calculator
How many bags of thinset for a tile job from area and label coverage. Click any i for detail.
Tile area
Area (sq ft)
i
Area
Floor or wall area to be set. |
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|---|---|
Coverage per bag (sq ft)
i
Coverage
From the bag for your trowel notch — often ~40–90 sq ft for a 50 lb bag. |
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Waste (%)
i
Waste
Cuts, uneven substrate, and mixing leftover. |
How to use this calculator
- Enter the tiled area.
- Enter coverage from the bag for your trowel size.
- Add a waste percent.
- Round-up bags are shown automatically.
Results explained
Thinset coverage depends on trowel notch, tile size, and substrate flatness. Manufacturers print sq-ft coverage per bag for common trowels — use that number rather than a generic guess. Large-format tile and thick-bed work burn through bags faster.
Quick reference: thinset
bags = ceil(area × (1 + waste%) / coverage_per_bag).
| Item | Detail |
|---|---|
| Small mosaic | Often higher coverage / bag |
| Large-format | Often lower coverage / bag |
| 1/4×3/8 trowel | Common floor starting point |
| Always | Read your bag’s chart |
Confirm mortar type (modified / unmodified) for your tile and membrane.
How the estimate is built
bags = ceil(area × (1 + waste/100) / coverage).
Example scenario
100 sq ft, 40 sq ft/bag, 10% waste → effective 110 ÷ 40 → 3 bags.
FAQ
Modified vs unmodified?
Membranes and porcelain often specify one or the other — follow the tile/membrane manufacturer.
Do walls use the same coverage?
Coverage charts differ; use the wall row on your bag if listed.
What about mastic?
This page is for thinset mortar bags, not premixed mastic.
Can I stretch thinset?
Starving the bond causes failures — buy enough for full ridges.