How this calculator works
This runs our tile calculator on the area. Each tile covers its own size plus a 3 mm joint, so the tiles are the area plus waste divided by that. Boxes use the coverage on the box. Adhesive follows the trowel notch, grout the volume of the joints, and tile backer boards (1200 × 800 mm) cover the surface.
Worked example: a 3 × 2.5 m floor (7.5 m²) in 300 × 300 mm tiles takes 90 tiles in 9 boxes, 37 kg of adhesive (2 bags of 20 kg), 2.9 kg of grout and 9 backer boards. In 600 × 600 mm tiles (1.44 m² boxes, 15% waste, a 12 mm notch) it is 24 tiles in 6 boxes.
Materials by area (300 × 300 mm tiles, 3 mm joints, 10% waste)
Boxes of 1 m²; 10 mm notch adhesive.
| Area | Tiles | Boxes | Adhesive bags | Grout bags |
|---|---|---|---|---|
| 2 × 1.5 m | 36 | 4 | 1 | 1 |
| 3 × 2.5 m | 90 | 9 | 2 | 1 |
| 4 × 3 m | 144 | 14 | 3 | 1 |
| 5 × 4 m | 240 | 22 | 5 | 2 |
Tips before you buy
- Buy all the tiles from one batch and check the shade on each box.
- Dry-lay a row across the room and set out from the centre, so the cuts at the walls are equal.
- Use a flexible adhesive over underfloor heating, on timber and for large or porcelain tiles.
- Wait for a new screed to dry before you tile.
- Keep a spare box for repairs.
Tools & materials for this project
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Frequently asked questions
How many tiles do I need for a 3m x 2.5m floor?
90 tiles of 300 × 300 mm with 3 mm joints and 10% for cuts (82 without any waste), which is 9 boxes at 1 m² a box.
How much adhesive and grout do I need?
For 7.5 m² about 37 kg of adhesive (2 bags of 20 kg) and 2.9 kg of grout (1 bag of 5 kg).
Do I need tile backer board?
Over a timber floor or a stud wall, yes: it gives a stable, flat, waterproofable surface. This floor takes 9 boards of 1200 × 800 mm.
How much extra tile should I buy?
10% for a straight layout, 15% for diagonals, large tiles or patterns, and a spare box for repairs.
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Related calculators & guides
Estimates only. Results assume standard materials and simple shapes. Supplier products vary, and the final call on quantity, structure and safety is yours. Check your local code and your supplier's guidance before ordering.