Tile Calculator
Work out how many tiles and boxes a floor or wall needs, grout joints included.
Last reviewed September 19, 2026
Result
Enter length and width to see the result.
https://calcgallery.com/flooring-tile/tile-calculator/
Results are estimates for planning only. Actual needs vary with site conditions, products and workmanship. Always confirm quantities with your supplier and follow local building codes and manufacturer instructions. Read the full disclaimer
How to use it
- Measure the floor or wall, or enter the total area if you already know it.
- Enter the tile size. Use the real tile dimensions, not the nominal ones printed on the box.
- Set the grout joint. It is part of what each tile occupies, so it changes how many fit.
- Pick the layout. Diagonal and herringbone cut more tiles at the edges and need a bigger allowance.
How it is calculated
Each tile occupies its own size plus one grout joint on each of two edges. That rectangle is the tile module:
Tile module = (tile length + joint) × (tile width + joint)The number of tiles is the area divided by that module, with the layout’s allowance applied and the result rounded up:
Tiles = ceil( area ÷ tile module × (1 + waste) )
Boxes = ceil( tiles ÷ tiles per box )Boxes are rounded up separately, which is why the box count sometimes jumps while the tile count barely moves. You cannot buy three quarters of a box.
The allowance is not padding. Every tile that meets a wall is cut, and the offcut is only reusable if another edge happens to need that exact width. A straight lay wastes least. A diagonal wastes more because every perimeter cut is an angle. Herringbone wastes most, because the pattern repeats in a way that cannot be nudged to fit the room.
Practical tips
Measure the tile, do not trust the box. A tile sold as 12 inch is often 11.8, and a 600 mm tile is often 595. Manufacturers size to the nominal module including a joint. If you use the printed size you will be a tile or two short.
Dry lay before you fix anything. Set out a row along the longest wall and see where the cuts fall. Shifting the start point by half a tile can turn two slivers at the edges into two comfortable half tiles, which looks better and breaks less.
Order from one batch. Tiles are made in runs and the shade shifts between them. Boxes bought a fortnight apart can be visibly different on the same floor. Buy the whole job at once and check the batch number on every box.
Keep the offcuts until the job is finished. The piece you cut for one corner is often exactly what the opposite corner needs. Sweeping them up on day one guarantees you cut two tiles where one would have done.
A bigger tile is not always fewer cuts. Large-format tile leaves less room for error on an uneven floor, and one broken 600 mm tile costs what four small ones do. On a floor that is out of level, smaller tiles forgive more.
With your numbers
- Tile module = (12 in + 0.125 in) × (12 in + 0.125 in)
- Tiles before waste = 120 ft² ÷ the module = 118
- With 10% waste = 130
- Boxes = 130 ÷ 10 per box, rounded up to 13
Quick reference
Tiles at the edges get cut and the offcuts are rarely reusable, so this includes an allowance for the layout you picked.
| Job | Tiles to buy |
|---|---|
| 5 × 8 ft bathroom floor, 12 in tiles | 44 |
| 10 × 10 ft room, 12 in tiles | 108 |
| 10 × 12 ft room, 12 in tiles | 130 |
| 12 × 15 ft room, 18 in tiles | 87 |
| 100 ft² of 6 × 24 in plank tile | 108 |
| 3 × 3 m room, 300 mm tiles | 108 |
| 4 × 5 m room, 600 mm tiles | 61 |
| 20 m² of 300 × 600 mm tile | 121 |
Common questions
- How many 12 inch tiles do I need for a 10 by 12 foot room?
- 130 with a 1/8 in grout joint and a 10% allowance for a straight lay. Without the joint it looks like 120, which is the mistake that sends people back to the shop.
- Why does the grout joint change the number of tiles?
- Because a 12 in tile with a 1/8 in joint occupies 12.125 in, not 12. On one tile that is nothing. Across a 12 ft run it is most of a tile, and across a whole floor it is several.
- How much extra should I buy?
- Around 10% for a straight lay, 15% for a diagonal, and 20% for herringbone or chevron. Angled cuts waste more because the offcut from one edge rarely fits another. Pick the layout above and the allowance follows.
- Should I buy extra tiles for later repairs?
- Yes, a box if you can. Tile production runs vary in shade and a discontinued line cannot be matched at all. A spare box in the loft is the difference between replacing a cracked tile and replacing a floor.
- Does this work for walls as well as floors?
- Yes. The maths is the same. Wall tiles are often thinner and more fragile, so breakage is a little higher, but the allowance for the layout already covers that.
- What if my room is not a rectangle?
- Split it into rectangles, work out each one, and add the tile counts. Round up once at the end. For an alcove or a doorway, measure the area you are actually tiling rather than the overall footprint.