What are iOS upgrades and why do they matter?
Every September, Apple rolls out a major update to the software that powers your iPhone. Each release comes with a new number — iOS 17, iOS 18, iOS 27 and most recently iOS 27 in September 2026.
These major releases contain new features designed to make your phone easier and more enjoyable to use. They also offer new functionality for app developers to make their apps more capable. On top of the cool new features, each new release brings key performance and security upgrades that keep your phone running smoothly and safely.
Between major releases, Apple also rolls out a series of minor releases (ie iOS 26.1, iOS 26.2 etc) which primarily fix bugs and patch any newly discovered security gaps.
It’s a good idea to update your phone as soon as the next version is available. Updating to the latest iOS version, even these minor releases, is an important step for phone security. Plus, if your iOS version falls too far behind, you may not be able to use certain apps.
iOS 27 should be available to download starting mid September – assuming your phone is compatible. On each new release (with some exceptions, like iOS 18 and notably iOS 27), Apple drops support for a generation of iPhones, meaning that generation won’t be able to get iOS updates anymore. If your iPhone is older than six or seven years old, it may not be eligible (we’ll get to that below).
iOS Version And App Compatibility
As we mentioned above, new versions of iOS come with new features that app developers can take advantage of. For example, iOS 18 debuted Dynamic Island, and iOS 26 had a redesigned look and iOS 27 is introducing a smarter, AI-enabled Siri.
As the app developers change their apps to support the latest versions of iOS, their apps might not be compatible with older iOS versions anymore. Supporting old iOS versions costs money, and since few users are using older versions, it ends up not being worth it for developers to support them.
Many large app developers have a policy of supporting the current iOS version and the previous iOS release. So if you have an iPhone that's one generation behind, all of your apps should work flawlessly … until the new update rolls around next September, at which point, some apps may stop working on your phone.
If you're wondering about a specific app, make sure to check out our App Compatibility Checker. It will tell you which operating system the app requires, and which phones will run the app (and for how long)!
iOS Security Updates
The security features and patches provided by Apple’s iOS updates are a crucial part of protecting your phone. Without them, your data and accounts could be vulnerable to attackers.
Apple builds security patches into each new iOS release, as well as patching older versions of iOS. Apple is a bit cagey about this, but our read is that — like the app developers — they are committed to supporting the current and one previous major iOS release.
Occasionally, Apple releases security patches for iOS versions prior to one generation back. For example, a patch was pushed for iOS 15 last September. But these aren’t regular security updates like newer versions get, so if your iOS version is older than two generations, you may have some vulnerability in terms of security.
What iOS is my phone on and why does it matter?
When it comes to what your phone can do and how long it'll last, the iOS version it supports is more important than the age or the model. Here’s a quick overview:
- iOS 18 iPhone XR and XS could keep up with the latest system features.
- iOS 26 ended support for the iPhone XS, XS Max and XR.
- iOS 27 is a bit of an exception, as all models compatible with iOS 26 will also be compatible with iOS27.
Knowing your phone's iOS version is important because it directly impacts whether you get the latest innovations, crucial security updates and the ability to run the newest apps. Being on an older iOS version isn’t the worst thing, but past a certain point, it’s a good idea to upgrade. Below, we’ll look at each iOS version, what phones are compatible with it and when you might need to get a new phone.
iOS 27: Which iPhones are compatible with the new iOS update?
iPhones from the iPhone 11, iPhone SE (second generation) and up (roughly, those released in 2017 or later) will be able to upgrade to iOS 27, which will be released in September 2026. The update will get you the latest interface, the new features we looked at above, and crucial security upgrades for your phone.
To update, you’ll need to make sure you have enough storage on your phone. If you don’t have enough free space, clear some up by deleting unused apps, pictures or files.
You can update your phone by going to Settings > General > Software Update. Make sure your phone is plugged in, and try to pick a time when you won’t need your phone for half an hour or more.
Scroll to the bottom of this article for a full list of which iPhone models and their latest compatible iOS.
Note: all iOS 26 compatible iPhones will also be compatible with iOS 27.
iOS 18 and Older: iPhones two or more updates behind
As an owner of an older model iPhone, you’re already (at least) two major operating systems behind: the iPhone Xr and Xs series were not compatible with iOS 26.
That means developers will gradually stop supporting your iOS version. By now, you’ve probably seen the “Cannot download“ message, pictured below, when trying to install an app incompatible with your current iOS.
Many apps will support iOS 27 and iOS 26 but increasingly, they’ll drop support for iOS 18.
Being on an older iOS version also introduces security vulnerabilities, since you’re not receiving regular updates and Apple doesn’t guarantee it’ll patch known security flaws.
To keep your phone as secure as possible, if you own an iPhone X or earlier model, we recommend upgrading your phone to an iPhone SE 3rd Gen, iPhone 12 or more recent model. Those models will continue to receive software support for another 2 years.
If you'd like to compare different iPhone (and even Android) models side by side, we built a nifty comparison tool with all the important info, including expected end of iOS support date.
Is there a specific app that you just can't live without? Use our compatibility tool to determine what devices can run that app (and for how long!)
The ‘Goldilocks Zone’ for iPhones one major update behind
Usually, when Apple releases a major new iOS update, it drops support for at least one generation of older iPhones. Last year, that was the iPhone XR, iPhone XS and iPhone XS Max.
Those newly unsupported iPhones enter what we call the “Goldilocks Zone.” They’re one major iOS version behind, but they’re not obsolete: they can still run almost all popular apps and continue to receive important security updates for another year, just won't be newly released features. In other words, they’re not brand new, but they’re not too old either — they’re just right.
This year, however, things are different. Apple didn’t drop support for any additional iPhones with iOS 27. That means there isn’t a new generation of iPhones sitting one major update behind — and, as a result, there is no Goldilocks Zone this year.
Last year’s Goldilocks phones — the iPhone XR, iPhone XS and iPhone XS Max — are now another year older. While they may still work perfectly well, app compatibility will increasingly become a concern as developers raise their minimum iOS requirements.
Curious which apps are likely to stop working on these older iPhones? We’ve compiled a list based on more than 400 apps in our database. While it’s not exhaustive, it covers most popular apps and gives you a clear overview at a glance. Scroll to the bottom of this article or skip to it by clicking here.
How long does it take to install an iOS update?
An iOS update generally takes between 30 minutes and an hour. This can vary based on factors like your internet speed, the size of the update, and the amount of free storage on your device.
To install the update as quickly as possible, clear up enough free space before installing it, connect to a stable Wi-Fi network and plug in your phone to a charger.
iOS 27: Most interesting new features
Here are some of the highlights of the newly released iOS 27:
- Smarter Siri: Let's be honest, sometimes Siri just doesn't get it. But that’s (supposedly) about to change. With new AI-powered capabilities, Siri is set to become smarter, more helpful, and better at understanding what you actually mean. There’s also a new Siri app that keeps track of your previous conversations, making it easier to pick up where you left off.
- Your iPhone should feel faster: Apple says apps can launch up to 30% faster, new photos can appear in Photos up to 70% faster, and AirDrop transfers can be up to 80% faster. Of course, take those numbers with a grain of salt—an iPhone 11 isn’t suddenly going to keep pace with an iPhone 17 Pro.
- More child safety features: More peace of mind for parents: Kids need permission before visiting new websites or downloading new apps, and during setup, parents can choose exactly which system apps their kids can access.
Full list of models and their latest compatible iOS
iPhone: iOS3 (3.1.3)
iPhone 3G: iOS4 (4.2.1)
iPhone 3GS: iOS6 (6.16)
iPhone 4: iOS7 (7.1.2)
iPhone 4S: iOS9 (9.3.5)
iPhone 5: iOS10 (10.3.4)
iPhone 5C iOS10 (iOS10.3.4)
iPhone 5S iOS12 (12.5.5)
iPhone 6: iOS12 (12.5.5)
iPhone 6 Plus: iOS12 (12.5.5)
iPhone 6S: iOS15 (15.6)
iPhone 6S Plus: iOS15 (15.6)
iPhone SE 2016: iOS15 (15.6)
iPhone 7: iOS15 (15.6)
iPhone 7 Plus: iOS15 (15.6)
iPhone 8: iOS16
iPhone 8 Plus: iOS 16
iPhone X: iOS16
iPhone XR: iOS18
iPhone XS: iOS18
iPhone XS Max: iOS18
iPhone SE 2020: iOS 27 (latest available version)
iPhone SE 2022: iOS27 (latest available version)
iPhone 11: iOS27 (latest available version)
iPhone 11 Pro: iOS27 (latest available version)
iPhone 11 Pro Max: iOS27 (latest available version)
iPhone 12 Mini: iOS27 (latest available version)
iPhone 12: iOS27 (latest available version)
iPhone 12 Pro: iOS27 (latest available version)
iPhone 12 Pro Max: iOS27 (latest available version)
iPhone 13 Mini: iOS27 (latest available version)
iPhone 13: iOS27 (latest available version)
iPhone 13 Pro: iOS27 (latest available version)
iPhone 13 Pro Max: iOS27 (latest available version)
iPhone 14: iOS27 (latest available version)
iPhone 14 Plus: iOS27 (latest available version)
iPhone 14 Pro: iOS27 (latest available version)
iPhone 14 Pro Max: iOS27 (latest available version)
iPhone 15: iOS27 (latest available version)
iPhone 15 Plus: iOS27 (latest available version)
iPhone 15 Pro: iOS27 (latest available version)
iPhone 15 Pro Max: iOS27 (latest available version)
iPhone 16: iOS27 (latest available version)
iPhone 16 Plus: iOS27 (latest available version)
iPhone 16 Pro: iOS27 (latest available version)
iPhone 16 Pro Max: iOS27 (latest available version)
iPhone 16e: iOS27 (latest available version)
iPhone 17: iOS27 (latest available version)
iPhone 17 Pro: iOS27 (latest available version)
iPhone 17 Pro Max: iOS27 (latest available version)
iPhone 17e: iOS27 (latest available version)
iPhone Air: iOS27 (latest available version)
