What is the tile's work size?

Understanding Tile Work Size: Manufacturing Dimensions Explained

The work size is the manufacturing dimension of tiles.

Due to manufacturing technology reasons, the porcelain 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.

Like the colour shade, the work size is also displayed on the pack, as follows:
20 x 20 cm (W 198 mm x 198 mm) where 198 mm stands for the manufacturing dimension.
Or:
20 x 20 cm – Size 01