Metric Count (NM) – NM stands for meters per gram of yarn. The NM designation would be noted either before or after a number indication the number of meters in 1 gram of yarn: NM 10 or 10 NM meaning there are 10 meters of yarn per gram. Plied yarns are marked NM 2/10 with the first number indicating the number of plies and the second number giving the meters per gram per ply.
Ply/Plying – Plying is the process of twisting two or more plys of yarn around each other to create a balanced Yarn. This Wikipedia article on Plying describes the process.
Yarn Weight – While many people speak English all over the world, The UK, The US and Australia have developed different names for their Yarn Weights, some of which don’t actually match up! This Wikipedia article on YarnWeight should help. Also worth remembering, that when a Yarn Weight includes “ply” as part of the name (i.e.2-Ply), this has nothing to do with how many plys the yarn is constructed from! All in all, Yarn Weight names are really confusing , which is why we’ve also included the Metric Count.