Will Apple Watch Series 9 fit your old case?
Yes, your old Apple Watch case should work for your Apple Watch Series 9 as long as it is the Apple Watch Series 7 or later. The Series 7 has slightly bigger sizes than the 6 and the bezels are different so Series 6 cases won’t work. If you have a 7 or 8 case right now, it should be able to work with no problem.
Will Apple Watch Series 9 fit your old band?
This answer depends on which version of the Apple Watch Series 9 you have bought. The 41mm version of the Apple Watch is compatible with any of the previous bands that are for the 38mm, 40mm, or 41mm watches. If you have the 45m Apple Watch Series 9, any 42mm, 44mm, and 45mm bands are compatible with it.
Can the Watch Ultra band fit your Apple Watch Series 9?
Yes, as long as you have the 45mm Apple Watch Series 9, the Apple Watch Ultra band will work with it. The same can be said for the Apple Watch Ultra 2, which can use the bigger watch bands from the Series 9. If you happen to have both of the new watches and picked the 45mm Series 9, they can share the same watch bands.
The future of the Apple Watch
Apple Watches have been relatively uniform since their launch. Though the bezels change, allowing for a slightly bigger screen, most of the accessories have remained compatible between generations. Unlike the iPhone 15 and iPhone 15 Pro Max, you can throw most cases on and they tend to work without worries. This is unlikely to change in the future.
We have recently heard rumors of a different band system for the Apple Watch X but this doesn’t mean older bands won’t be compatible in some form. However, a different design will likely mean you will have to buy a case for Apple’s next major watch.