You can mark your chain with cable ties  - but they can really hurt your hands especially when its cold.

Or you can paint marks on your chain - which works pretty well until you need to get your chain re-galvanised when it can be a pain.

Or you can splash out a bit or cash and buy these splendid chain markers! These used to come in packets of 10 which no-one liked, so we now sell them individually so you can mix and match to your heart's content!