What is the work-size or caliber?

The work size is the manufacturing dimension of ceramic tiles. Due to manufacturing technology reasons, the tiles leaving the kiln may be of slightly different dimensions. Therefore, during the grade sorting stage, they are divided and grouped into batches of the same dimensions, according to the standards tolerance provided for by specific regulations, that is to say a slight variation in work size – a matter of mm at most.
As with the colour shade, the work size is also displayed on the packaging with a number, for example: work-size 9.