Quick answer: A 4 m × 3 m floor (12 m²) with 60 × 60 cm tiles and 3 mm joints needs 12 ÷ 0.3636 = 33 tiles, or 37 with 10% extra: 10 boxes of 4.
How it's calculated
Each tile covers its own size plus one joint in each direction: (length + joint) × (width + joint). Tiles = area ÷ that coverage, then add the waste allowance and round up.
Boxes = tiles ÷ tiles per box, rounded up. The box label usually also gives the coverage in m², which you can check against the area.
For walls, measure each wall's width × height and subtract large openings such as doors and windows before entering the total area.
Worked examples
- 4 m × 3 m, 60 × 60 cm, 3 mm joint, 10%: 12 ÷ 0.3636 × 1.1 = 36.3 → 37 tiles, 10 boxes
- 12 ft × 10 ft, 12 × 12 in, ⅛ in joint, 10%: 120 ÷ 1.021 × 1.1 = 129.3 → 130 tiles
Tiles per square metre (3 mm joint)
| Tile size | Tiles per m² |
|---|---|
| 30 × 30 cm | 10.89 |
| 40 × 40 cm | 6.16 |
| 45 × 45 cm | 4.87 |
| 60 × 60 cm | 2.75 |
| 60 × 120 cm | 1.38 |
| 80 × 80 cm | 1.55 |
| 120 × 120 cm | 0.69 |
Frequently asked questions
How many 60 × 60 tiles are in one square metre?
2.78 tiles without joints (1 ÷ 0.36), or 2.75 with 3 mm joints.
How much extra tile should I buy?
About 10% for straight patterns and 15% for diagonal, herringbone or rooms with many corners.
Should I include the grout joint?
Yes for an accurate count with small tiles; with large tiles and thin joints the difference is small.
How many 60 × 60 tiles do I need for 12 m²?
33 tiles cover it exactly with 3 mm joints. Buy 37 so you've got 10% spare for cuts and breakage.
How much grout do I need?
Look at the table on the grout bag. It lists kilograms per m² for each tile size and joint width, and big tiles with thin joints need surprisingly little.
Should I keep spare tiles?
Yes, keep a few or a whole box. Colour shifts slightly between production batches, so a tile you buy in two years' time may not match.