If your phone's running iOS 17 it should run iOS 18 just fine.
However, for Apple Intelligence you'll need an iPhone 15 Pro / Pro Max or one of the iPhone 16 models.
If you haven't decided to order an iPhone 16 or iPhone 16 Pro just yet, the arrival of iOS 18 on Monday 16 September may change your mind. The latest version of Apple's iPhone operating system has some features designed specifically for Apple's most powerful iPhones.
However, if those features don't matter to you then iOS 18 is available for a lot of older iPhone models, with a few important exceptions. As a rule of thumb, if you're currently running iOS 17 then your iPhone will also run iOS 18.
But there are a few things lurking in the small print, and there's also Apple Intelligence to consider. Here's what you need to know.
iOS 18, Apple Intelligence and your iPhone
According to Apple, iOS 18 is compatible with the iPhone SE 2, the iPhone XR, the iPhone XS and the iPhone 11 onwards, including the various Pro, Mini, Plus and Pro / Pro Max variants.
Some of iOS 18's features require specific hardware, however. The new eye tracking accessibility feature needs at least an iPhone 12 or SE 3, and the new haptic Music features also need the iPhone 12. Live audio transcriptions for calls needs the iPhone 12 or later, and the new InSight features in the TV app need iPhone 11 or later.
The big issue for most of us, though, is Apple Intelligence. Those features aren't here yet – they're coming later in the year, and for the UK they're scheduled for December – but when they arrive the minimum requirement is the iPhone 15 Pro, iPhone 15 Pro Max or any of the iPhone 16 range. That means if you want those features but don't have the last-gen Pro/Pro Max or one of this year's models, you'll need to upgrade your iPhone.
