Apple will have a slightly longer serial number for repair parts for its Apple Watch, Mac, iPhone and others starting October 1.

Ahead of the expected launch of the Apple Watch Series 8, the iPhone 14 and more, Apple has sent a memo to authorized service providers on how the new serial numbering system works.
The new format is 18 digits for repair parts, which means that they will need to update their equipment and machines to recognize the parts beginning October this year.
The upcoming change in serial number will likely apply to new Apple products, such as future Macs, Apple Watches, iPads and iPhones.
In the same vein, Apple informed its service providers in 2020 that it will adopt a randomized serial number for Apple products, which was a shift to the previous system. Before the change, service providers and customers could determine where and when an Apple product was made.