Tile calculator
How many boxes of wall tiles to buy for a room, worked out from the tiled height and what one box covers.
How the number is worked out
- Measure the wall to tile. The distance round the room, and the height the tiles go up to. To the ceiling, that is the room's height.
- Find the area. The distance round the room times the tiled height.
- Take off the doors. Each comes off up to the tiled height: its width times the lower of its height and the tiled height. Windows come off only when the tiles go to the ceiling.
- Add the extra for cuts. The planner starts at 10%, a labelled example. Change it if the tile's fitting guide says more.
- Count the boxes. The area with the extra, divided by what one box covers, rounded up to whole boxes.
A worked example
A room 3 m by 2 m and 2.4 m high, with one door 0.8 m wide and 2 m high. Boxes cover 1 m² and the extra for cuts is 10%. These are example figures, not a product.
| Working | Tiled to 1.2 m | Tiled to the ceiling |
|---|---|---|
| Distance round the room | 10 m | 10 m |
| Height tiled | 1.2 m | 2.4 m |
| Wall area | 12 m² | 24 m² |
| Less the door | 0.96 m² | 1.6 m² |
| Area to tile | 11.04 m² | 22.4 m² |
| With 10% for cuts | 12.144 m² | 24.64 m² |
| Boxes to buy | 13 | 25 |
| Left over | 0.856 m² | 0.36 m² |
The planner counts boxes by area. The box's label says how many tiles it holds, so multiply the boxes by that number to count the tiles. Copy the coverage from your own box: it changes the answer.
Mistakes that cost a box
- Using the room's height when the tiles stop lower. The tiled height sets the area. In the example it is 13 boxes to 1.2 m and 25 to the ceiling.
- Taking a window off when the tiles stop below it. A window that starts above the tiles takes nothing off them. The planner takes windows off only when the tiles go to the ceiling.
- Leaving out the extra for cuts. Cut tiles are waste. 10% is a starting figure. Diagonal and herringbone layouts, and large tiles in a small room, waste more.
- Rounding down. A box is sold whole, so the answer is always rounded up.
- Buying boxes from different batches. The shade can differ between batches. The box shows the batch.
Questions
Can I use it for a floor?
Yes. Choose Flooring, then Tiles, and enter what one box covers. A floor is counted from its area, with an extra for cuts, in whole boxes.
Do I take off the doors and windows?
Doors come off up to the height you tile to. Windows come off only when the tiles go to the ceiling, because below that the planner does not know where the sill is.
How much extra do I add for cuts?
The planner starts at 10%, a labelled example for tiles laid straight. The tile's fitting guide says more for other layouts. Change the figure to match.
Which box size does it start with?
A box that covers 1 m², with 10% extra. They are labelled examples, not a product. Change them to the figures on your box.
Does it count adhesive and grout?
Yes, if you enter what one bag covers, from the bag. It depends on the tile size, so without those figures the line tells you what to check.
How many tiles is that?
The planner counts boxes. Multiply the boxes by the number of tiles the box's label gives.