How to use this calculator
- Enter or choose area to cover.
- Enter or choose consumption rate.
- Enter or choose waste allowance.
- Enter or choose pack size.
- The packs to buy updates as you type. Use Copy result or Share to keep it.
Method
Quantity = Area × Rate × (1 + waste); Packs = ⌈Quantity ÷ Pack size⌉
- Rate
- consumption per m² from the datasheet
- waste
- allowance for spillage and the last unusable mix
Worked example
- Quantity = 25 × 4 × 1.10 = 110 kg.
- Packs = 110 ÷ 20 = 5.5 → 6 bags.
- Each bag covers 20 ÷ 4 = 5 m² before waste.
25 m² at 4 kg/m² with 10% waste needs 110 kg of adhesive, or 6 bags of 20 kg.
What the result means
Large-format tiles and uneven floors often need back-buttering or a bigger notch, which raises consumption; check the datasheet for those cases.
Assumptions and limits
- Rate and pack size use the same unit.
- Primer, levelling compound and grout are not included.
Questions
Why does the trowel size matter?
A larger notch leaves a thicker bed, so more adhesive per m². Datasheets list the rate for each notch size.
Can I use leftover adhesive later?
Opened powder adhesive keeps for a limited time if sealed and dry; mixed adhesive must be used within its pot life.
Please note: Quantities are estimates. Confirm requirements with your engineer or supplier before ordering materials.