The numbers are the tile's nominal size in millimetres, width by length. A 600x600 tile is about 60 cm square, a 600x1200 is about 60 by 120 cm, and an 800x800 is about 80 cm square.
"About" matters. The nominal size is a name. The real size, which the standards call the work size, is set by the factory and can be a few millimetres smaller. You need both numbers when you plan a floor or compare suppliers.
Nominal size vs work size
ISO 13006 and EN 14411 use three terms. The nominal size is the name used to describe the tile. The work size is the size the manufacturer actually makes it to. The actual size is what you measure on a tile, following ISO 10545-2.
The standard then limits how far each tile can stray from the work size. For porcelain tiles in group BIa, technical sheets referring to EN 14411 commonly state a limit of ±0.6% of the work size, up to a maximum of ±2.0 mm, for the average of each tile's sides. Check which edition your contract cites, because editions differ.
A non-rectified 600x600 might have a work size a few millimetres under 600. A rectified tile is ground after firing and usually sits much closer to the nominal figure. See rectified vs non-rectified tiles.
Millimetres vs inches
Morbi factories work in millimetres. Buyers in the US often think in inches, and the conversions are not exact:
- 600x600 mm is about 23.6 x 23.6 inches, usually sold as 24x24.
- 600x1200 mm is about 23.6 x 47.2 inches, usually sold as 24x48.
- 800x800 mm is about 31.5 x 31.5 inches, usually sold as 32x32.
If you sell a 600x600 as 24x24, put the real millimetre work size on your box label and data sheet. Installers who set out a floor from the rounded inch figure will find the joints drifting over a long run.
Where each size is used
- 600x600: homes, shops, offices and public buildings. It is easy to handle, cut and lay, and the design choice is the widest.
- 600x1200: modern homes, offices and retail. The long format makes rooms look larger, but it shows lippage and warpage more than a square.
- 800x800: living areas, lobbies and showrooms. Fewer joints give a cleaner look, and it needs a flat screed and careful laying.
Our guide to standard floor tile sizes in Morbi covers the full range, from 300x300 to large slabs.
Why the difference matters to you
If you buy the same nominal size from two factories, their work sizes may not match. Tiles from different suppliers then cannot be mixed in one floor, even in the same colour.
The same is true within one factory for non-rectified tiles. They are sorted into calibres, or size groups, after firing. Read what calibre means before you place a repeat order.
Square metres per box also depend on the work size. Check the packing list to confirm how many tiles and square metres each box holds, and see tiles per box by size.
What to write in your order
- The nominal size and the work size in millimetres.
- Whether the tile is rectified or non-rectified.
- The tolerance you accept, referring to a named standard and edition.
- One calibre per design per shipment for non-rectified tiles.
Next step
A clear size line in the purchase order prevents a common dispute. We measure samples and production tiles against the agreed work size before loading. To plan your order, book a free sourcing review.