These are all the devices compatible with iOS 18 and iPadOS 18
Apple’s new iOS 18 and iPadOS 18 updates are mostly good news for users of older Apple devices—with the exception of 2018’s sixth-generation iPad, the new updates will run on all the same hardware that can run iOS 17 and iPadOS 17.
For iPhones, that will cover everything from the iPhone XR/XS and newer, including the second-gen iPhone SE; the seventh-gen iPad and newer; the third-gen iPad Air and newer; the fifth-gen iPad mini and newer; all 11-inch iPad Pros; and the third-gen 12.9-inch iPad Pro and later. Here are the full support lists:
It’s a bit odd that the seventh-gen iPad makes the cutoff while the sixth-gen model does not, given that both use the same Apple A10 processor. But the seventh-gen iPad has 3GB of RAM instead of 2GB. This is the same amount as the third-gen iPad Air and fifth-gen iPad mini—apparently that extra gigabyte is crucial for running iPadOS 18’s new features.
While this support list is fairly generous, Apple’s headlining “Apple Intelligence” AI features will be restricted to newer devices on the list. The situation is worst for the iPhone, which only supports Apple Intelligence on the iPhone 15 Pro and its A17 Pro chip—the regular iPhone 15 isn’t getting these features, and older phones will miss out on them as well. On the iPad, you’ll need an iPad Air or Pro with an M1 chip or newer.
Aside from Apple Intelligence, the company lists a few other features that require a newer device to work. The Smart Script handwriting enhancement feature requires an iPad with Apple M-series chip or an A14, cutting out a handful of older models with A10, A12, and A13-series chips. On the iOS side, live audio transcription, the Eye Tracking accessibility feature, and the Vocal Shortcuts accessibility feature require an iPhone 12 or newer.
https://arstechnica.com/?p=2030142