About this calculator
Enter the room size in metres and the tile size in centimetres, and get the number of tiles for the layout plus a sensible allowance for cuts and breakages.
The calculator counts whole rows and columns (partial tiles are cut from whole ones), so it gives a more realistic figure than dividing the area by one tile's area. Add the tiles per box to see how many boxes to order.
Worked examples
Real numbers, worked out by the same calculator. Press “Use these numbers” to try one above.
4 m × 3 m floor, 30 cm tiles
- Tiles to buy
- 154
- Tiles in the layout
- 14 × 10 = 140
- Floor area
- 12 m²
- Extra for cuts and breakages
- 14
- Boxes to buy
- 16 (10 per box)
A 4 m × 3 m floor with 30 × 30 cm tiles needs 154 tiles including 10% extra. That is 16 boxes.
Show the working
- Each tile with its grout gap takes 30.3 cm × 30.3 cm of floor.
- Rows: 4 m ÷ 0.303 m = 13.20132, rounded up to 14. Columns: 3 m ÷ 0.303 m = 9.90099, rounded up to 10. Layout = 14 × 10 = 140 tiles.
- Add 10% for cuts and breakages: 140 × 1.1 = 154 tiles (rounded up). Diagonal and herringbone patterns need 15 to 20%.
Bathroom wall 2.4 m × 2 m, 20 × 10 cm metro tiles
- Tiles to buy
- 264
- Tiles in the layout
- 12 × 20 = 240
- Floor area
- 4.8 m²
- Extra for cuts and breakages
- 24
- Boxes to buy
- 6 (50 per box)
A 2.4 m × 2 m floor with 20 × 10 cm tiles needs 264 tiles including 10% extra. That is 6 boxes.
Show the working
- Each tile with its grout gap takes 20.2 cm × 10.2 cm of floor.
- Rows: 2.4 m ÷ 0.202 m = 11.881188, rounded up to 12. Columns: 2 m ÷ 0.102 m = 19.607843, rounded up to 20. Layout = 12 × 20 = 240 tiles.
- Add 10% for cuts and breakages: 240 × 1.1 = 264 tiles (rounded up). Diagonal and herringbone patterns need 15 to 20%.
Large format 60 × 60 cm in a 5 m × 4 m room
- Tiles to buy
- 70
- Tiles in the layout
- 9 × 7 = 63
- Floor area
- 20 m²
- Extra for cuts and breakages
- 7
- Boxes to buy
- 18 (4 per box)
A 5 m × 4 m floor with 60 × 60 cm tiles needs 70 tiles including 10% extra. That is 18 boxes.
Show the working
- Each tile with its grout gap takes 60.2 cm × 60.2 cm of floor.
- Rows: 5 m ÷ 0.602 m = 8.305648, rounded up to 9. Columns: 4 m ÷ 0.602 m = 6.644518, rounded up to 7. Layout = 9 × 7 = 63 tiles.
- Add 10% for cuts and breakages: 63 × 1.1 = 70 tiles (rounded up). Diagonal and herringbone patterns need 15 to 20%.
How the number is worked out
Each tile takes up its width plus the grout gap. The room length divided by that gives the tiles per row, and the width gives the number of rows, both rounded up because a partial tile still needs a whole one. The total is then increased by your waste allowance.
How much extra?
- 10% for a simple straight layout
- 15 to 20% for diagonal, herringbone or small awkward rooms
- More for large-format or patterned tiles, which waste more at the edges
Always buy all your tiles from the same batch: shades can differ between production runs.
Measure carefully
Measure the longest length and width of the room, including any alcoves added separately. Subtract fixed items that won't be tiled, such as a bath, by running the calculator separately for each separate tiled area and adding the totals.
Frequently asked questions
How many tiles do I need for a room?
Divide each side by the tile size plus gap, round up, multiply the two, and add 10% for cuts.
How much extra should I buy?
10% for straight layouts, 15 to 20% for diagonal or herringbone.
Is the tile size in centimetres?
Yes, and the room in metres. The grout gap is in millimetres.
Why not just divide the areas?
Partial tiles at the edges still use a whole tile, so counting rows and columns is more accurate.
Does it work for walls?
Yes. Enter the wall's width and height as the area length and width.
Formulas tested against hand-worked answers. Last reviewed 29 September 2026. These calculators do arithmetic only; they are not financial, tax or legal advice.