Tile adhesive = area × coverage for your trowel × (1 + waste). 600 × 600 mm tiles usually go down with a 10 mm notch at about 4.5 kg/m², so 20 m² needs 99 kg with 10% extra: 5 bags of 20 kg. Tiles over 600 mm also need back-buttering, about 1.2 kg/m² more.
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Tile Adhesive Calculator
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Tile adhesive
99kg
Bags of 20 kg
5 bags
Trowel notch
10 mm (3/8″) suggested
Back-buttering
No
Coverage used
4.5 kg/m²
Area per bag
4.4 m²
Coverage varies by product and background: the figure on the adhesive bag takes priority. Check contact by lifting a tile now and then.
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Adhesive = 20.0 m² × 4.50 kg/m² × 1.10 = 99 kg → 5 bags
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Generated with myconstructioncalculator.com. Estimates for planning and ordering only; verify against drawings and specifications.
Formula
Notch = from tile size (or your choice)Coverage = typical kg/m² for that notch (+ 1.2 kg/m² if back-buttered)Adhesive (kg) = area × coverage × (1 + waste)Bags = ⌈adhesive ÷ bag size⌉
Worked example
20 m² of 600 × 600 mm floor tiles, 10% waste, 20 kg bags:
Suggested notch: 10 mm (⅜ in): no back-buttering at 600 mm
Coverage ≈ 4.5 kg/m²
Adhesive = 20 × 4.5 × 1.1 = 99 kg → 5 bags
Trowel guide and typical coverage (cementitious powder adhesive)
Tile size
Notch
Typical coverage
m² per 20 kg bag
Mosaic (≤ 100 mm)
4 mm
1.5 kg/m²
13.3
Up to 300 mm
6 mm (¼″)
2.5 kg/m²
8.0
Up to 450 mm
8 mm (5/16″)
3.5 kg/m²
5.7
Up to 600 mm
10 mm (⅜″)
4.5 kg/m²
4.4
Large format
12 mm (½″) + back-butter
6.7 kg/m²
3.0
These are planning figures: use the coverage printed on your adhesive.
Frequently Asked Questions
How much tile adhesive do I need per m²?
Typically about 2.5 kg/m² with a 6 mm notch (small wall tiles), 3.5 kg with 8 mm, 4.5 kg with 10 mm and 5.5 kg with 12 mm (large floor tiles), for cementitious powder adhesive. The bag gives the exact coverage for that product.
What size trowel should I use for tiles?
As a guide, 4 mm for mosaics, 6 mm (¼ in) up to 300 mm tiles, 8 mm up to 450 mm, 10 mm (⅜ in) up to 600 mm and 12 mm (½ in) for large format, then check coverage by lifting a tile.
When should tiles be back-buttered?
For large-format tiles (over about 600 mm), tiles with ribbed or uneven backs, and floors in wet or outdoor areas, where near-full adhesive contact is needed.
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