Short answer: tile adhesive (thinset) takes about 3 kg per m² with a 6 mm notched trowel and 5 kg per m² with a 10 mm trowel; a 20 kg bag covers 4–6.5 m². Grout takes much less: about 0.24 kg per m² for 300 × 600 mm tiles with a 3 mm joint, and about 0.8 kg per m² for small 100 mm tiles.
Tile adhesive: the trowel decides
The notch on the trowel sets how thick the bed of adhesive is, and the tile size sets the notch: bigger tiles need a deeper notch so the whole back of the tile is in contact.
| Tile size and trowel notch | Per m² | One 20 kg bag covers | One 50 lb bag covers |
|---|---|---|---|
| Mosaics – 4 mm notch (3/16 in V-notch) | 2 kg/m² | 10 m² | 122 ft² |
| Tiles up to 300 mm (12 in) – 6 mm notch (¼ × ¼ in) | 3.1 kg/m² | 6.5 m² | 79 ft² |
| Wall tiles up to 450 mm (18 in) – 8 mm notch (≈ 5/16 in) | 4 kg/m² | 5 m² | 61 ft² |
| Floor tiles up to 450 mm (18 in) – 10 mm notch (¼ × ⅜ in) | 5 kg/m² | 4 m² | 49 ft² |
| Larger tiles – 12 mm notch (½ × ½ in) and back-buttering | 8.5 kg/m² | 2.4 m² | 29 ft² |
The calculator's rates, from LATICRETE coverage data, with back-buttering for large tiles, before any spare. The figure on your adhesive bag comes first.
How to use it: area × rate per m². A 10 m² kitchen floor in 400 × 400 mm tiles with a 10 mm notch takes 10 × 5 = 50 kg, so three 20 kg bags. In US sizes: 10 m² is 108 ft², and a 50 lb bag covers about 49 ft² with that notch, so three 50 lb bags.
Two things change the figure:
- Back-buttering. Large-format tiles (60 cm / 24 in and up), tiles in showers and outdoor tiles are usually laid with adhesive on the floor and a thin coat on the back of the tile, so that no hollows are left. In the US, the ANSI installation standard asks for at least 80 % contact in dry areas and 95 % in wet areas and outdoors. Back-buttering is the main reason the last row of the table is so much higher.
- Uneven floors. A floor that is out of level eats adhesive. Level it first with self-levelling compound; the screed calculator works out the bags.
The rate printed on your adhesive bag comes first: products differ.
Grout: tile size × joint width × depth
Grout fills the joints, so it depends on how much joint there is per m²: small tiles have far more joint than large ones.
| Tile size | Joint depth | 2 mm joint | 3 mm joint | 5 mm joint | Per 100 ft², ⅛ in joint |
|---|---|---|---|---|---|
| 100 × 100 mm | 8 mm | 0.51 kg | 0.77 kg | 1.28 kg | 16.6 lb |
| 200 × 200 mm | 8 mm | 0.26 kg | 0.38 kg | 0.64 kg | 8.3 lb |
| 300 × 300 mm | 8 mm | 0.17 kg | 0.26 kg | 0.43 kg | 5.5 lb |
| 300 × 600 mm | 10 mm | 0.16 kg | 0.24 kg | 0.4 kg | 5.2 lb |
| 400 × 400 mm | 10 mm | 0.16 kg | 0.24 kg | 0.4 kg | 5.2 lb |
| 600 × 600 mm | 10 mm | 0.11 kg | 0.16 kg | 0.27 kg | 3.5 lb |
| 600 × 1200 mm | 10 mm | 0.08 kg | 0.12 kg | 0.2 kg | 2.6 lb |
| 800 × 800 mm | 10 mm | 0.08 kg | 0.12 kg | 0.2 kg | 2.6 lb |
| 12 × 12 in | 8 mm | 0.17 kg | 0.25 kg | 0.42 kg | 5.5 lb |
| 12 × 24 in | 10 mm | 0.16 kg | 0.24 kg | 0.39 kg | 5.1 lb |
| 16 × 16 in | 10 mm | 0.16 kg | 0.24 kg | 0.39 kg | 5.1 lb |
| 24 × 24 in | 10 mm | 0.1 kg | 0.16 kg | 0.26 kg | 3.4 lb |
| 24 × 48 in | 10 mm | 0.08 kg | 0.12 kg | 0.2 kg | 2.6 lb |
From the calculator's formula, (length + width) ÷ (length × width) × joint depth × joint width × 1.6 kg/L, before any spare. The joint depth is the tile thickness the calculator assumes; thicker tiles take more.
The formula the calculator uses:
kg per m² = (tile length + tile width) ÷ (length × width) × joint depth × joint width × 1.6
with the sizes in mm and 1.6 kg per litre for cement grout. For 300 × 600 mm tiles, 10 mm thick, with a 3 mm joint: (300 + 600) ÷ (300 × 600) × 10 × 3 × 1.6 = 0.24 kg per m². A 20 m² bathroom wall then takes about 5 kg of grout, so one 5 kg bag — buy a second if the room has many cuts and corners.
Epoxy grout is heavier and more expensive; follow its own coverage chart.
A full bathroom, worked out
Floor 5 m² in 600 × 600 mm tiles, walls 20 m² in 300 × 600 mm tiles, 3 mm joints:
| Item | Floor (5 m²) | Walls (20 m²) |
|---|---|---|
| Adhesive rate | 8.5 kg/m² (12 mm + back-buttering) | 4 kg/m² (8 mm) |
| Adhesive | 42.5 kg | 80 kg |
| Grout rate | 0.16 kg/m² | 0.24 kg/m² |
| Grout | 0.8 kg | 4.8 kg |
In bags: 7 bags of 20 kg adhesive (122.5 kg) and one 5 kg bag of grout plus a small one. The tile calculator works out the tiles and boxes for the same room.
Frequently asked questions
How much tile adhesive do I need per m²?
2 kg/m² for mosaics (4 mm notch), about 3 kg for tiles up to 30 cm (6 mm), 4 kg for wall tiles up to 45 cm (8 mm), 5 kg for floor tiles up to 45 cm (10 mm) and about 8.5 kg for large tiles with back-buttering.
How many m² does a 20 kg bag of tile adhesive cover?
About 6.5 m² with a 6 mm notch, 5 m² with an 8 mm notch and 4 m² with a 10 mm notch.
How much grout do I need per m²?
For 300 × 300 mm tiles with a 3 mm joint, about 0.26 kg/m²; for 600 × 600 mm, about 0.16 kg/m²; for 100 × 100 mm, about 0.77 kg/m².
How much thinset for 100 square feet?
With a ¼ × ⅜ in notch (floor tiles up to 18 in), about two 50 lb bags. With a ½ × ½ in notch and back-buttering for large tiles, about four bags.
Calculators in this guide
Enter your own sizes for an exact answer.
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