The quick answer: a 10 × 10 ft floor is 100 square feet. With 12 × 12 inch tiles you need 100 tiles, or 110 tiles once you add the usual 10% for cuts and breakages. With larger 12 × 24 tiles it is about 55 tiles.
Below you will find the simple formula, a table for the most popular tile sizes, and how much extra to buy for different layouts. To skip the maths, use the tile calculator, which works in feet or metres and adds waste for you.
Tiles for a 10×10 room at a glance
These figures are for a plain rectangular 10 × 10 ft (100 sq ft, about 9.3 m²) floor laid in a straight pattern.
| Tile size | Area per tile | Tiles (exact) | Tiles with 10% extra |
|---|---|---|---|
| 12 × 12 in | 1 sq ft | 100 | 110 |
| 18 × 18 in | 2.25 sq ft | 45 | 50 |
| 12 × 24 in | 2 sq ft | 50 | 55 |
| 24 × 24 in | 4 sq ft | 25 | 28 |
| 6 × 24 in plank | 1 sq ft | 100 | 110 |
| 300 × 300 mm | 0.09 m² | 104 | 114 |
| 600 × 600 mm | 0.36 m² | 26 | 29 |
Grout joints of 2–3 mm make each tile cover slightly more floor, but the difference is small. Ignore it and let the waste allowance cover you.
How to work it out yourself
- Measure the floor. Multiply length by width: 10 ft × 10 ft = 100 sq ft.
- Work out the area of one tile. Multiply its length by its width in inches and divide by 144. A 12 × 24 tile is 288 ÷ 144 = 2 sq ft.
- Divide floor area by tile area. 100 ÷ 2 = 50 tiles.
- Add waste. 50 × 1.10 = 55 tiles. Always round up to a whole tile, then up to a whole box.
If the room is L-shaped, split it into rectangles, work out each area and add them together. Take off any area under fixed kitchen units or a bath, but not under a vanity or toilet, which you tile around.
How much extra should you buy?
The waste allowance depends on the layout and on how many cuts the room needs.
- 10% for a straight (grid) layout in a simple room.
- 15% for a diagonal layout, herringbone or a room with lots of corners, pipes and doorways.
- 20% for large-format tiles in a small, awkward room, where one bad cut can waste a whole tile.
It is also worth keeping a few spare tiles after the job. If one cracks in a few years, the exact colour and batch may no longer be on sale.
Buying tiles by the box
Tiles are usually sold in boxes that cover a fixed area, such as 10.76 sq ft (1 m²) or 16 sq ft. Divide your total area including waste by the box coverage and round up. For 110 sq ft of 12 × 12 tiles in 10 sq ft boxes, that is 11 boxes.
Check the batch or shade number printed on every box. Tiles from different batches can vary slightly in colour, so buy everything at once and mix tiles from several boxes as you lay them.
Don’t forget grout and adhesive
Tile is only part of the order. For a 100 sq ft floor you will also need:
- Tile adhesive or thinset. Coverage depends on the trowel notch. Larger tiles need a bigger notch, so they use more. Check the coverage chart on the bag and add 10%.
- Grout. The amount depends on tile size, joint width and tile thickness. The grout calculator works it out for you.
- Trim and spacers for edges, doorways and to keep joints even.
Common mistakes that leave you short
- Measuring only the main rectangle and forgetting door recesses or alcoves.
- Rounding down at each step instead of rounding up.
- Using a 10% allowance for a herringbone or diagonal pattern.
- Not checking that all boxes are from the same batch.
Frequently asked questions
How many boxes of tile do I need for a 10×10 room?
Take 110 sq ft (100 sq ft plus 10%) and divide by the coverage on the box. With boxes covering 15 sq ft, you need 8 boxes.
Are bigger tiles cheaper to lay?
Bigger tiles mean fewer grout lines and faster laying, but they need a very flat floor and can create more waste in a small room. In a 10×10 room, 12 × 24 is a good middle ground.
How many tiles for a 10×10 wall?
The maths is the same: 100 sq ft of wall needs the same number of tiles as 100 sq ft of floor. Take off the area of any windows or doors first.
Can I use the same numbers for a 12×12 room?
A 12 × 12 room is 144 sq ft, so multiply the figures above by 1.44. With 12 × 12 tiles, that is about 159 tiles including 10% extra.
Related: the DIY Project Budget & Materials Planner turns your measurements into quantities, costs and a shopping list.
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