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Tile Adhesive Calculator

Notch depth drives the quantity: about 1.6 kg/m² per mm.

Quick answer

With the default inputs: Tiling area 50 m² · Notch size 8 mm · Back buttering No back buttering etc.Adhesive per m² 12.8 kg/m²

Edit the inputs below to recalculate.
Length LWidth W
Area is the tiling area; consumption follows notch depth — about 3.5 kg/m² for a 6 mm notch and 6 kg/m² for 10 mm.

Inputs

m²

Result

Adhesive per m²
12.8kg/m²
Base for notch12.8kg/m²
Back buttering factor1.00
Flatness factor1.00
Total adhesive640kg
Bags (whole)32bags
Purchased weight640kg

Rule of thumb: each millimetre of notch gives about 1.6 kg/m² (8 mm notch is roughly 12-13 kg/m²), because the ridges only fill about half the volume. U, V and square notches plus trowel angle (45-60°) all shift the figure. Codes require full contact - at least 80% coverage on floors and external walls - so large format, external work and uneven bases need back buttering. Too little adhesive is the leading cause of hollow spots and detachment.

Formula

Base ≈ notch (mm) × 1.6kg/m²
Actual = base × back-buttering × flatness
Total = actual × area
Bags = ceil(total ÷ bag size)
50 m² of floor with 600×600 tiles on an 8 mm notch, no back buttering, flat base: 12.8 kg/m², 640 kg total, 32 bags of 20 kg. Adding back buttering (as large format requires) with the same notch raises it to 20.5 kg/m² and 52 bags.

How to work it out

  1. Pick the notched trowel by tile size: 6 mm notch up to 300 mm tiles, 8-10 mm for 300-600, 12 mm plus back-buttering beyond 800 mm.
  2. Check substrate flatness with a 2 m straightedge. Anything over 3 mm needs levelling — never build up the adhesive, since a thin-bed layer over 10 mm slumps and voids.
  3. Compute consumption: area × the unit rate for that notch. Single-sided application runs 4-6 kg/m²; large-format back-buttered work doubles it.
  4. Adjust for the substrate: concrete and cement render behave normally, while plasterboard and tiling-over-tile are non-absorbent and need the enhanced class.
  5. Divide by the bag weight and round up. Mixed adhesive is good for two hours; after that it is scrap and cannot be revived with water.

Where it goes wrong

Material and cost

C1 adhesive 30-80 CNY per 20 kg bag, C2 80-150, rapid-set adds 30%. Consumption 4-8 kg/m², that is 8-30 CNY/m². Bonding slurry 5-10 CNY/m² extra.

On site

Basis

FAQ

Why is the ratio not one to one?
A notch trowel leaves ridges separated by voids that must be filled when the tile is bedded. Ideally the ridges occupy half the volume, which is why an 8 mm notch uses about 12.8 kg/m² rather than a solid 12 kg. Notch shape, trowel angle and bedding pressure all change coverage - hence the requirement to lift a tile and check, not just eyeball the comb.
Why must large format tiles be back buttered?
They are stiff and heavy, so they cannot conform to the substrate the way small tiles do, and air trapped between the ridges cannot escape, leaving voids. Back buttering pushes the air out and raises contact area. Codes require two-sided application for tiles above 900×900 and for external thin-bed work. Without it, hollow spots and detachment are likely within a year or two.
Can cement be added to tile adhesive?
Never. Tile adhesive is a factory blend of cement with redispersible polymer and cellulose ethers; adding cement destroys the flexible polymer network, cutting bond strength and causing shrinkage cracks. Nor should sand be added, or water to a mix that has begun to set. Many hollow-tile failures trace to exactly this, and nothing shows until inspection.

Cite this page

Use this format in reports, method statements or coursework. The link is permanent.

Building Calculator. Tile Adhesive Calculator. 2026-10-25. https://jianzhujisuan.com/en/tile-adhesive

Results are estimating aids only and are not a design basis. Construction and final accounts must follow the drawings, the applicable standards and an approved method statement. Anything affecting structural safety, shoring or falsework must be checked by a suitably qualified engineer.