watchOS and compatible iOS versions

You're pairing your apple watch to your iPhone and suddenly there is a message: "This Apple Watch needs a newer version of iOS in order to pair" And your asking yourself "what am I doing wrong"

Well, mostly nothing. watchOS versions have requirements for the iOS on the iPhone it is pairing to.

To use an Apple Watch Series 11, you will need an iPhone 11 or higher and run iOS 26.x.x Same goes for the SE third gen and the Ultra 3rd gen.

The series 10 can be used with an iPhone XS or newer, running iOS 18. The Ultra 2 and the Series 9 can be paired to an iPhone XS or newer, running iOS 17.

So keep this information in mind if you're looking to buy a new Apple Watch when still using an older iPhone. If you're looking for a different watch and still running an older iPhone with iOS 16 or 15, keep in mind that you better can go and look for a refurbished watch, that is not allready running watchOS 26 when your iPhone is running iOS 18.