Tiler has measured 22 m² of wall tiles to fix using standard wall tile adhesive. You need the total adhesive in kg and the number of 20kg bags before the builder order is placed.
Tile Adhesive Calculator
Tiling
Coverage rates vary by product and substrate — always check the bag. Notch trowel size affects coverage significantly.
Reference: Boral Adhesive Coverage Guide
Results are estimates for planning purposes. Verify with current standards and a qualified professional.
1 What this calculator does
Calculates tile adhesive required in kilograms from the area to be tiled, adhesive type and waste factor. Coverage rates are based on manufacturer typical spreads for different adhesive types and tile sizes. Rounds up to whole bag quantities.
2 Formula & professional reasoning
Coverage rate (kg/m²) by adhesive type:
Standard wall tile adhesive: 4.0 kg/m²
Standard floor tile adhesive: 5.0 kg/m²
Large format tile adhesive (600mm+): 6.0-7.0 kg/m²
Epoxy adhesive: 3.5-4.5 kg/m²
Total kg = Area x Coverage rate x Waste factor (1.10 or 1.15)
Bags = Ceiling(Total kg / Bag size)
Adhesive coverage rate depends on the tile format (larger tiles require full back-buttering which uses more adhesive), the substrate condition (rougher or more porous substrates can absorb more adhesive) and the application method (notched trowel size). AS 3958 requires 95% back coverage for wet areas and 80% for dry areas -- larger notched trowels are needed to achieve this for larger format tiles, consuming more adhesive.
3 Worked examples
⚠️ Illustrative example only — not clinical or professional instruction.
Basic
Wall tiles -- standard adhesive
Given: Area: 22 m² | Tile type: wall tiles | Adhesive: standard | Waste: 10%
Working:
Coverage: 4.0 kg/m² | Total: 22 x 4.0 x 1.10 = 96.8 kgAnswer: Total adhesive: 96.8 kg | Order 5 x 20kg bags
💡 5 bags = 100 kg with 3.2 kg spare. Spare can be used for patch repairs or additional cuts.
Standard
Large format floor tiles -- back-buttering required
Given: Area: 18 m² | Tile: 600x600mm | Adhesive: large format | Waste: 15%
Working:
Coverage rate large format: 6.5 kg/m² | Total: 18 x 6.5 x 1.15 = 134.6 kgAnswer: Total adhesive: 134.6 kg | Order 7 x 20kg bags
💡 Large format tiles require full back-buttering in addition to the notched trowel bed, increasing consumption significantly. Confirm coverage rate with the specific adhesive manufacturer.
Advanced
Epoxy adhesive for chemical-resistant wet area
Given: Area: 12 m² | Tile type: pool surrounds | Adhesive: epoxy | Waste: 10%
Working:
Epoxy coverage: 4.0 kg/m² | Total: 12 x 4.0 x 1.10 = 52.8 kgAnswer: 52.8 kg epoxy adhesive | Order 6 x 10kg kits
💡 Epoxy adhesive comes in two-component kits (resin + hardener). Calculate volume required then match to kit sizes. Epoxy has a pot life of 30-45 minutes -- only mix what you can use in time.
4 Sanity check
AS 3958 back coverage requirements
Wet areas: 95% minimum back coverage | Dry areas: 80% minimum | Verify with a test tile pull during installation
Standard adhesive bag sizes
15kg and 20kg for most powder adhesives | Epoxy kits: 5kg, 10kg, 20kg | Always order full bags -- no returns
Notched trowel size by tile format
Tiles under 300mm: 6mm V-notch | 300-450mm: 10mm square notch | 450-600mm: 12mm square | 600mm+: 15mm square with back-butter
Pot life
Standard powder adhesive: 20-30 minutes working time after mixing | Epoxy: 30-45 minutes | Rapid-set: 10-15 minutes
5 Common errors
| Error | Cause | Consequence | Fix |
|---|---|---|---|
| Using wall tile adhesive for floor tiles | Not selecting the correct adhesive type for the application | Wall adhesive does not have sufficient strength for floor loads -- tiles debond under foot traffic | Select adhesive specifically rated for the application. Floor adhesive has higher compressive and shear strength. For wet areas, use a flexible or waterproof adhesive. Epoxy adhesive is required for chemical exposure. |
| Not back-buttering large format tiles | Applying adhesive only to the substrate with large tiles | Low back coverage -- tiles hollow in the centre, prone to cracking under load | For tiles 400mm and larger, apply adhesive to both the substrate (notched trowel) and the back of the tile (back-buttering with a flat trowel). This is required by AS 3958 for wet areas and best practice for all large format tiles. |
| Mixing too much adhesive at once | Wanting to minimise the number of mix batches | Adhesive stiffens before being used -- wasted material and potential adhesion problems from using partially set adhesive | Only mix the adhesive quantity that can be used within the working time (pot life). This varies by temperature: hotter conditions shorten pot life significantly. In summer, work in smaller batches. |
| Not allowing adhesive to cure before grouting | Grouting as soon as tiles are set | Adhesive movement during grout curing causes joint cracking -- especially visible in 1-3mm joints | Allow standard adhesive minimum 24 hours to cure before grouting. In damp or cold conditions, extend to 48 hours. Rapid-set adhesive can be grouted sooner -- check the manufacturer's datasheet. |
6 Reference & regulatory links
🇦🇺 Australia
7 Professional workflow
Common tools used alongside this one: