Calculate tile adhesive bags, tubs or complete kits from the area you will tile and the product's coverage. Enter a single rate or a published range, add reserve and subtract usable stock to estimate what to buy.
How much tile adhesive do I need?
Start with the area that will actually be tiled, then use the coverage of your chosen adhesive for the intended application. Divide the area by the square metres or square feet covered by one bag, tub or complete kit. Add your reserve and round the total up to whole packs.
This tile adhesive calculator also works as a thinset mortar calculator when you enter the coverage of a bagged thinset product. It supports either coverage per pack or consumption in kilograms per square metre. It does not assume that every 20 kg or 25 kg bag covers the same area.
Measure the tiled surface, not the spare tiles
For a floor rectangle, multiply length by width. For a wall, multiply its tiled length by its tiled height. Split irregular shapes into rectangles that do not overlap, or enter a known measured area. Deduct windows, doors or fixed untiled areas only where adhesive will not be applied. Include tiled reveals and returns as additional areas.
Use the installed surface area. Do not add the percentage of spare tiles you plan to buy. Cut offcuts do not all become extra bonded floor area. Adhesive has its own material allowance, entered separately in this calculator. Do not subtract individual grout joints from a normal surface-area estimate based on the manufacturer's coverage.
Which coverage figure should I enter?
Find the technical sheet for the exact product, pack size and market. Match its rate to your trowel, tile backing and installation method. A figure for one trowel or a particular adhesive bed is not automatically valid for another.
For example, ARDEX X 7 lists approximately 5.1 m² at a 3 mm bed from a 20 kg bag. Those conditions belong with the coverage figure. The example is useful for reading a label, but it is not a universal rate or a product recommendation.
If the manufacturer gives a range, enter both endpoints. The calculator uses lower coverage per pack for the higher material estimate. With consumption in kg/m², the direction is reversed: higher consumption produces the higher requirement. You can enter the two numbers in either order.
As a published range example, the LATICRETE 323 technical sheet for Malaysia gives approximately 6.5 to 7.5 m² from a 25 kg bag with a 6 × 6 mm square-notch trowel. Use the current data for the product you are buying, rather than carrying that range over to a different adhesive.
Why trowel size alone is not enough
The notches create ridges that change when the tile is bedded. A 10 mm notch does not simply mean a solid 10 mm layer beneath the tile. The ARDEX X 7 technical sheet relates trowel choice to tile size, the surface, the profile behind the tile and the contact required. This is why the calculator asks for product coverage instead of assigning one consumption number to every notch size.
Back buttering means applying adhesive to the back of the tile as part of the specified fixing method. Include it in the rate you enter. If your coverage data excludes it, obtain an adjusted consumption figure from the manufacturer or a representative measured trial. A general waste allowance is not a substitute for material needed by the application method. Follow the product's instructions and check adhesive transfer during installation.
The calculation in plain numbers
Coverage method: pack equivalents = net tiled area ÷ coverage per complete pack.
Consumption method: pack equivalents = net tiled area × consumption in kg/m² ÷ net material kg per pack.
Add pack equivalents for all areas using the same product and pack size. Multiply by 1 + reserve percentage ÷ 100, then round up once. Subtract complete usable packs already in stock, stopping at zero. Multiply the remaining whole packs by your entered price.
In consumption mode, the weight basis must match. Use dry powder consumption with the dry powder weight of a bag, or ready-mixed product consumption with the net contents of a tub. Do not add mixing-water weight to a powder bag. For multicomponent products, use coverage per complete kit so the supplied components stay together.
Example: 20 m² and a coverage range
Suppose one complete pack is expected to cover 4 to 5 m² for your planned application. For 20 m², the initial requirement is 20 ÷ 5 to 20 ÷ 4, or 4 to 5 pack equivalents. Add a chosen 10% reserve to get 4.4 to 5.5, then round up to 5 to 6 complete packs.
If you already have 1 usable pack, the purchase range is 4 to 5 packs. At an entered price of €25 each, that is €100 to €125. The higher purchase estimate covers the lower coverage value you entered. It does not guarantee the outcome if actual site conditions fall outside that range. The Try an example button loads these illustrative figures.
For a single consumption figure, a 20 m² surface at 4 kg/m² needs 80 kg before reserve. With 10% added, 88 kg divided by a 20 kg bag gives 4.4 bags, rounded up to 5. These example rates explain the maths and must be replaced with your product data.
Common questions
Can walls and floors use different coverage rates?
Yes. Add them as separate areas and enter a suitable rate for each. They can share the final pack total only when the adhesive product and pack size are the same. Calculate different products or sizes separately.
How much reserve should I add?
The calculator starts with an editable 10%. Choose an allowance for the measurements and handling conditions of your job. Check whether the rate already includes waste before adding it again. If the surface needs levelling or another preparation layer, estimate that material separately instead of increasing adhesive use without checking the permitted bed depth.
Can I use an opened bag from a previous job?
Count only complete usable packs of the matching product and size. Check condition, storage and shelf life. Leave uncertain or partial stock out of this calculation. An opened or part-used multicomponent kit should not be counted as a complete kit.
Does this include grout or waterproofing?
No. It covers the adhesive purchase at your entered price. Plan tiles with the tile calculator, joints with the grout calculator and a specified preparation layer with the self-leveling compound calculator. Primer, waterproofing, tools, delivery and labour are separate costs.
