You're tiling a rectangular room, and you want to use square tiles. However, you don't want to use a tile cutter. Instead, you want to pick a size of square tile that will fill your room perfectly and evenly.

Luckily, there is an easy way to compute exactly what size of square tiles you need to cover a rectangular room. Here's what you need to do:

1. Measure your room.

Measure the room you plan to tile. Most tiles in Australia are measured in millimetres, and as a result, you should convert your measurement into millimetres. To convert metres into millimetres, multiply them by 1,000.

For example, if your room is 2 metres by 3.5 metres, it is 2,000 mm by 3,500 mm.

2. Create squares based on the shortest side of your rectangle.

Now, take the shortest side of your rectangle, and mentally create squares based on that measurement. To continue with the above example, the shortest side of the room is 2,000 mm so your first square should be 2,000 mm by 2,000 mm. You can fit one square of this size into your rectangular room. When you place that theoretical square in your room, you have a remaining area that measures 1,500 mm by 2,000 mm.

In this case, you could only fit one square in the room, but in other cases, you may be able to fit several squares in the space. In particular, if your room is very long and narrow, you will be able to fit in multiple squares.

3. Create more squares.

Now, to hone further in on your perfect tile size, it's time to create more squares based on the shortest side of your remaining space. In this example, your next square needs to be 1,500 mm on each side. When you place that into your remaining area, you have a leftover space measuring 500 mm by 1,500 mm.

Then, you must create more squares to fill this area. These squares will measure 500 mm by 500 mm. You can fill the remainder of your space with these squares, and as a result, you are done with the calculation.

4. Order tiles to match your smallest squares.

Once you have broken your entire room into theoretical squares, it's time to order tiles in the size of your smallest squares. In this case, you can fill your entire floor with tiles measuring 500 mm by 500 mm.

To calculate exactly how many tiles you need to order, take the length of the tiles you are ordering, and divide this number into the length and width of your rectangular room. Then, multiply those numbers together -- the product is the number of tiles you need.

In this case, your room is 2,000 mm wide, and 2,000 mm divided by 500 mm is four. As a result, you need four tiles to cover the width of your room. Its length of 3,500 mm requires seven tiles. Multiply four and seven together to get 28.

5. Choose smaller square tiles if you want.

The above calculation helps you determine the largest square tiles you can use to cover a rectangular floor evenly. If you want smaller tiles, you can break your measurement into smaller squares by dividing each side by 4 until you find a size you like.

For example, instead of 500 mm square tiles, you could use 125 mm square tiles. If that's still too big, divide by four again. In this case, the result is 31.25 mm, but in many other cases, the result may be whole numbers.

When you are ready to order, contact a tile company, and let them know the size and number of square tiles you want.