Minimum MacOS requirements to work with iOS/iPadOS 18.x.x

Apple doesn't publish this information on the pages describing iOS and iPadOS.

But a rule of thumb seems to be that if you look at the requirements for an iPhone or iPad that originally shipped with a given version of iOS or iPadOS, those are the requirements for managing earlier iPhones or iPads that you upgrade to that iOS or iPadOS version.

This suggests that

----------

Syncing to a Mac or PC requires:

• macOS Catalina 10.15 or later using the Finder
• macOS High Sierra 10.13 through macOS Mojave 10.14.6 using iTunes 12.9 or later
• Windows 10 or later using iTunes 12.12.10 or later (free download from apple.com/itunes/download)

----------

In practice, people have had mixed experiences using Macs running High Sierra to manage iPhones running iOS 17 and iOS 18. If the requests for help on these forums are accurate, sometimes things work, sometimes they do not, sometimes people get things to work by unwieldy workarounds (like extracting a file out of Xcode) that should not be necessary.

But I have not seen a lot of posts complaining about things not working with Catalina and later (where the syncing function is in the Finder). So my guess is that a Mac running Big Sur should have no problem managing an iPad – any iPad – running iPadOS 18.

Syncing won't be an issue. In general, the kinds of issues you are likely to encounter when the comparable versions of macOS and iOS get too far apart will occur in different specific apps at different rates depending on individual feature requirements.

For a practical example - you can sync iMessage from the current version of iOS 18 all the way to Catalina - unless you want to use Contact Key Verification. Then you need iOS 17.2 (or later) and macOS 14.2 (or later). On the other hand, Photos has almost no sync limitations.

So, sync in general is no issue, and issues tend to involve more advanced features on a per App basis when they do occur.

Can someone please confirm what will happen if I upgrade my iPad mini to iPadOS 18.x.x ? Will I still be able to sync with my MacBook on Big Sur?

Confirmed. Go ahead and upgrade.

If you are asking about iCloud features, rather than about using a Mac to manage an iPad, see:

System requirements for iCloud - Apple Support

There are also ways that Macs and iPads can work together that fall under the category of Continuity features.

Continuity features and requirements for Apple devices - Apple Support