During calibration, the tiles are measured after production and sorted into the same sizes, so-called calibers. This makes it possible to lay with very narrow joints of approx. 2 mm. The term "calibrated" says nothing about the edge shape. These can be sharp-edged but also slightly rounded. Uncalibrated tiles require a joint width of 5 mm to compensate for permissible dimensional tolerances.
Source: bauwion
