Tile adhesive calculator
Estimate thinset or tile adhesive kilograms and bags from area, trowel notch, and optional back-buttering.
Loading tool…
Recommended next step
Continue with related tools
After using Tile adhesive calculator, continue with Tile grout calculator.
Continue this path
Tools selected to complete the same task.
Tool guide
Tile adhesive calculator: how it works
Practical information to understand the result and use this tool correctly.
About Tile adhesive calculator
Enter a known area or a rectangle, then pick a square-notch trowel. Coverage in kilograms per square metre is a planning rate for that notch: 1.5 for 3 mm, 3 for 6 mm, 4 for 8 mm, 5 for 10 mm, 6.5 for 12 mm, and 8 for 15 mm. Bags to buy are that rate times the area, times one plus waste, plus an optional back-butter skim, divided by the bag size and rounded up.
A 4 by 3 metre floor with a 10 mm notch uses about 5 kg/m², or 60 kg before waste. At 10 percent waste and 25 kg bags that is 3 bags. The same floor with a 12 mm notch and back-buttering adds about 1 kg/m² of skim, so the order rises. A 4 m² mosaic wall on a 3 mm notch stays near 1.5 kg/m² before waste.
Presets cover a 20 cm wall, a 60 cm floor, a large-format slab with back-butter, and a mosaic sheet. Waste defaults to 10 percent. Back-buttering is a flat skim on the tile back, common above about 300 mm on a side; it is not a second full notch bed. The rates assume a square notch that collapses to roughly half the notch volume, which is the usual field estimate, not a lab coverage from one brand.
Nothing is uploaded. Empty areas, waste above 30 percent, and bag sizes outside 2 to 25 kg are rejected. The tile calculator counts pieces and boxes. The grout calculator sizes the joint. This one only sizes the adhesive under the tile.
How to use it
- 1Choose metres or feet, then a known area or a rectangle.
- 2Pick the trowel notch that matches the tile and the substrate.
- 3Set bag size, waste, and turn on back-buttering only for large format.
- 4Review kilograms per square metre, bags to order, leftover, and optional cost, then copy the order.
Frequently asked questions
- How much thinset do I need?
- Multiply the notch rate by the area, add waste, and divide by the bag size. A 10 mm square notch is about 5 kg/m² before waste. A 6 mm notch is about 3 kg/m². Back-buttering adds about 1 kg/m² of skim.
- What is the formula?
- Order kg = area × notch rate × (1 + waste) + area × 1 kg/m² if back-buttering. Notch rates are 1.5, 3, 4, 5, 6.5, and 8 kg/m² for 3, 6, 8, 10, 12, and 15 mm square notches. Bags are that mass divided by the bag size, rounded up.
- When should I back-butter?
- Large-format tile, often over 300 mm on a side, and any tile that must reach full contact usually gets a flat skim on the back. This tool adds 1 kg/m² for that skim. It does not replace the trowel bed.
- Does the calculation leave the browser?
- No. Areas, notch choice, prices, and the bag count stay on your device.