Tiles are counted from the area, the tile size and the joint: every tile takes up its own size plus one joint width in each direction. The calculator then adds a cutting allowance, rounds up to whole boxes and estimates the grout.
Example: a 3.2 × 2.8 m bathroom floor is 8.96 m². With 60 × 60 cm tiles and 3 mm joints, each tile covers 0.603 × 0.603 m, so the bare floor takes 24.6 tiles. Add 10% and round up: 28 tiles, or 7 boxes of 4. In feet: a 10 × 12 ft floor (120 ft²) in 12 × 12 in tiles with 1/8 in joints takes 117.5 tiles, so 130 tiles with 10% extra.
Tiles per m² and per ft²
With the usual joint for each size. Before waste.
| Tile | Joint | Tiles per m² | Tiles per ft² |
|---|---|---|---|
| 10 × 10 cm | 2 mm | 96.1 | 8.93 |
| 20 × 20 cm | 2 mm | 24.5 | 2.28 |
| 30 × 30 cm | 3 mm | 10.9 | 1.01 |
| 30 × 60 cm | 3 mm | 5.47 | 0.51 |
| 60 × 60 cm | 3 mm | 2.75 | 0.26 |
| 60 × 120 cm | 2 mm | 1.38 | 0.13 |
| 3 × 6 in (subway) | 1/16 in | 83.5 | 7.76 |
| 4 × 4 in | 1/16 in | 93.9 | 8.73 |
| 6 × 6 in | 1/8 in | 41.3 | 3.84 |
| 12 × 12 in | 1/8 in | 10.5 | 0.98 |
| 12 × 24 in | 1/8 in | 5.30 | 0.49 |
| 24 × 24 in | 1/8 in | 2.66 | 0.25 |
Metric and US tiles are not the same size: a “30 × 30” tile is 300 mm, a “12 × 12” is 304.8 mm. Enter the size printed on the box, in the unit it is printed in.
Grout: why the joint matters more than the area
Grout fills the joints, so what matters is how many meters of joint there are and how wide and deep they are. Small tiles have far more joint per square meter than large ones. The calculator uses the formula grout makers print on their bags, with mixed cement grout at 1.6 kg per liter:
| Tiles, thickness, joint | Grout per m² | Per 100 ft² |
|---|---|---|
| 10 × 10 cm, 6 mm thick, 2 mm joint | 0.38 kg | 7.9 lb |
| 30 × 30 cm, 8 mm, 3 mm | 0.26 kg | 5.2 lb |
| 30 × 60 cm, 9 mm, 3 mm | 0.22 kg | 4.4 lb |
| 60 × 60 cm, 9 mm, 3 mm | 0.14 kg | 2.9 lb |
| 60 × 60 cm, 9 mm, 5 mm | 0.24 kg | 4.9 lb |
| 12 × 12 in, 3/8 in thick, 1/8 in joint | 0.32 kg | 6.5 lb |
| 3 × 6 in subway, 5/16 in, 1/16 in joint | 0.40 kg | 8.1 lb |
Epoxy and urethane grouts are lighter or heavier than cement grout; their bags give their own coverage. Whatever the type, buy a little more than the estimate, because some always stays in the bucket and on the sponge.
Before you order
- Batch: buy every box from the same production lot (printed on the box). Shades vary between lots, and it shows on a floor.
- Layout: start from the center of the room so the cut tiles at the edges are equal, and dry-lay a row before you mix anything.
- Large tiles: tiles of 60 cm (24 in) and more need a flat floor and often a leveling system; they also break more often in cutting, which is why the allowance goes up to 15%.
Need the area first? The square footage calculator handles L-shaped rooms. Once zet4u is saved on your phone, both work offline, in the tile aisle as much as at home.
Frequently asked questions
How much extra tile should I buy?
10% for a straight lay in an ordinary room, 15% for diagonal or herringbone patterns and large-format tiles, up to 20% for rooms with many corners, pipes or steps. Discontinued colors cannot be matched later, so the extra is also your stock for repairs.
How many 12 × 12 tiles are in a square foot?
Just under one: with a 1/8 in grout joint each tile covers 12.125 × 12.125 in, so 100 ft² takes 98 tiles before waste. A 60 × 60 cm tile with a 3 mm joint covers 0.364 m², or 2.75 tiles per m².
How do I work out tiles for a wall with a window?
Measure the whole wall (width × height), then take off the window and door areas, and enter the result as the area. Keep the waste allowance as it is: the tiles cut around the opening are what it is for.
How much grout do I need?
It depends on the joint, not only on the area: narrow joints between big tiles take very little. The formula on grout bags is kg per m² = (A + B) ÷ (A × B) × thickness × joint × 1.6, with the sizes in mm. 60 × 60 cm tiles 9 mm thick with 3 mm joints need about 0.14 kg/m²; 10 × 10 cm mosaic-like tiles need almost three times as much.
Sources
Last checked: