When tiles are made they are made slightly bigger than needed before firing. During the firing process the clay they are made from shrinks. Due to clay being a natural substance, the amount of shrinkage may vary from batch to batch. So if the tile being produced is going to be a 60x60cm tile, known as its nominal size, it will be made slightly bigger than 60x60cm before firing. After firing the tiles are measured, often using lasers, to find the actual size of each tile produced. The tiles produced may differ from each other, for example 59.9x59.9 and 59.8x59.8. These tiles are sorted into the same sizes on the production line. These sizes are called Calibres. So all the 59.8x59.8 size tiles will end up in the same Calibre boxes which will be marked.
The calibre may be expressed as a number or set of numbers and letters. This process avoids slightly different size tiles ending up in the same boxes. When installing tiles it is important to check you have all the calibre, sometimes shown as calibre, to avoid sizing issues when fitting the tiles. Tiles that have rectified edges don't often have calibres, as these are produced larger then the edges are ground down to produce a very precise size. Should you require more tiles of the same calibre you should make a note of which calibre you require. For help when ordering additional tiles for your project, speak to our customer service team on 01473 805959.