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Thinset & Tile Adhesive Calculator

Work out the adhesive a tiling job needs from the trowel notch, which is what actually sets the coverage.

Computed in your browser — nothing you enter is uploaded. Figures are presented for United States against IRC 2024, and every formula is cited under regulatory standards below.

Last verified 2026-08-26 · v1.0.0

Market
Imperial · sales tax

Adhesive required

3 bags

Check your inputs

Coverage rates are typical for cement-based adhesive. Check the specific product — rates vary by 20% between brands and between standard and lightweight formulations.

Adhesive required
132.28 lb
Coverage rate
5 kg/m²
Bag size
44.09 lb
Surplus in the last bag
0 lb

Running these inputs gives 3 bags as the adhesive required. Note that area to tile sits at the low end of the range this calculator was checked against, so treat the output as indicative rather than settled. Expect some drift against the real job; the calculation is solid but conditions on site are not. Currently reading for United States under IRC 2024 — pick a different market above and the figures re-cast accordingly.

Estimated cost — your price

This site holds no price list for this material — local prices vary too much to publish honestly. Enter your supplier's price and the result is costed with it.

Preliminary estimate, not certified engineering. This tool produces an indicative quantity calculation for planning purposes only — it is not a certified structural analysis, a guaranteed material takeoff, or a substitute for building department approval. Always verify measurements on-site and have a licensed contractor or structural engineer review any load-bearing, code-sensitive, or safety-critical work before purchasing materials or starting construction. Spotted an arithmetic or standards error? Report it to contact@craftquantities.com with your inputs — confirmed fixes become pinned regression tests.

[Schema Verified] Computed in alignment with American Concrete Institute (ACI 318-19) formulas and International Residential Code (IRC 2024) spatial boundaries.

Regulatory standards & verification citations

  • Coverage by notch size — TCNA Handbook and adhesive manufacturers' published data. Larger tiles require larger notches and consume substantially more.
  • TCNA requires 80% mortar coverage for dry interior and 95% for wet areas and exterior — back-buttering is usually needed to achieve it on large formats

Your workspace

Most jobs need more than one number. Add the calculators you need next and they open right here, underneath this one — your figures stay on screen and nothing is lost to a page change.

Frequently asked questions

Why does the trowel notch decide the quantity?
Because it sets the depth of the adhesive ridges, and it is those ridges that collapse to form the bed. A 6 mm notch lays about 3 kg/m²; a 20 mm half-round about 9. The tile size matters only because it determines which notch you must use.
What is back-buttering and do I need it?
A skim of adhesive on the back of the tile as well as the substrate. On large-format tile it is the practical way to reach the coverage the standards require — 80% for dry interior, 95% for wet areas — because a notched bed alone rarely achieves it under a big tile. It adds about a third to consumption.
Why do I keep running out?
Almost always substrate flatness. Adhesive fills every hollow, and a floor that is 5 mm out over two metres absorbs a surprising amount of it. Levelling first costs less than the extra adhesive and gives a better result — filling deviation with adhesive is how tiles end up hollow-sounding.