iPhone and Apple Watch Compatibility update and correction.
I was wrong about Apple Watch compatibility in my previous post, but Apple’s chart is what makes it confusing.
I had stated earlier that you needed iOS 18 to use an Apple Watch, or else you were out of luck. Turns out, there is a hierarchy based on which versions of watchOS and iOS you have to determine compatibility. Having iOS 18 puts you at the top of the food chain (or tangled web in this case) and makes all watches compatible.
This isn't an issue for an iPhone XS or later user since they do have iOS 18, but it is a confusing mess if you have an iPhone X or earlier. I know these people are few and far between, but I'm still seeing these devices out in the wild.
What made me assume that you must have iOS 18 in order to use an Apple Watch? It was Apple of course in their own words:
To set up and use an Apple Watch, you need iPhone XS or later with iOS 18 or later.
Initially I thought this was an error, until I tried doing some other pairing experiments. When I wrote my first piece, I tried pairing a Series 5 Watch with an iPhone SE 1st gen several times, and each time it would not work. Then I tried pairing a Series 3 watch to the same iPhone, with no luck.
According to Apple’s chart though, both should have worked:
As you can see here, for a Series 5, you need an iPhone 6s or later, and iOS 13 or later. The iPhone SE 1st gen meets the criteria, but won’t pair, and it wouldn’t pair to a Series 3 that I tried three separate times.
Based on this information, I concluded that you must have iOS 18 moving forwards in order to use an Apple Watch.
But that’s not true.
I tried a 4th time to pair my Series 3 to my iPhone SE 1st generation over a week later, and it did work. Why it didn’t work the first three times is beyond me, even with restarting both devices, but maybe the iOS 15 and watchOS 8 update pathways or servers were down on that day? Who would’ve actually noticed though since these versions of the OS are obsolete.
After successfully pairing my iPhone SE 1st gen to a Series 3, I then decided to do some other experimentation. My iPhone X qualifies even more to pair with a Series 5 according to the chart, but it also wouldn’t pair saying my version of iOS (iOS 16) was out of date. The chart once again makes it seem compatible because it says I need iOS 13 or later and an iPhone 6s or later. Aaaah!
These are my results for trying to pair different watches to different iPhones up to this point:
iPhone SE 1st gen paired to a Series 5 - FAIL
iPhone SE 1st gen paired to a Series 3 - FAIL
iPhone SE 1st gen paired to a Series 3 (2nd attempt) - FAIL
iPhone SE 1st gen paired to a Series 3 (3rd attempt) - FAIL
iPhone X paired to a Series 3 - PASS
iPhone X paired to a Series 5 - FAIL
iPhone SE 1st gen paired to a Series 3 (4th attempt) - PASS
Long story short, this chart from wikipedia really tells you a more up-to-date compatibility of Apple Watches and iPhones for those iPhones that don’t update past iOS 16.
It turns out an iPhone is limited to what version of watchOS it can pair to than the generation of Apple Watch itself.
This chart explains why my Series 5 wouldn’t pair with my iPhone SE 1st gen or my iPhone X because the Series 5 was already updated to watchOS 10. If it was still on watchOS 9, it would work with the iPhone X and iPhone 8 but not the iPhone SE 1st gen.
New rules for Apple Watch compatibility with iPhones:
If your iPhone supports iOS 18, it will pair with any Apple Watch.
If you have an iPhone 8 or iPhone X, it will pair with a Series 4, Series 5, or SE 1st generation Apple Watch on watchOS 9 or earlier, and any Apple Watch before that.
If you have an iPhone 6S, SE 1st generation, or iPhone 7, you can pair a Series 3 Apple Watch or earlier.