This tip is designed to be a one stop shop to find out what iOS you can use if you are able to install a specific Mac OS X.
Now updated for iOS 11. Including a method to downgrade to iOS 10.3.3!
Good news, iTunes 12.8, released September 12th, 2018 still supports Yosemite 10.10.5.
iOS - the operating system found on iPad, iPod Touch, and iPhone.
Mac OS X the operating system found on Apple's Macintosh computers since 2001, and some older models
that have been upgraded. Note: Apple has dropped the X moniker again in the name as of the introduction of Sierra. This should not confuse people running older Macs whose system number is not 10.0 or later.
Downgrading Mac OS X is possible in many cases, but your iOS is not at all. Downgrading a Mac is described here:
For iOS earlier than 5, see this tip:
So be sure to look this over before upgrading your iOS and backup/sync your iOS with your Mac:
Mac OS X 10.5.8 (Leopard) supports PowerPC Macs, iTunes 10.6.3, iOS 5.1.1.
Mac OS X 10.6.8 (Snow Leopard) supports Intel only Macs, but does support PowerPC applications, iTunes 11.4 and iOS 6, and iOS 7.
Mac OS X 10.7.3 (Lion) supports iCloud except for iCloud Drive in its current iteration and the new Notes.
Mac OS X 10.7.5 (Lion) (link explains the pitfalls of losing PowerPC applications) supports iTunes 220.127.116.11 (available from Software update as of 10/24/2015), iOS 8 and iOS 9.0.
Mac OS X 10.8 (Mountain Lion) is required for iTunes 12.3 and iOS 9.2 and iOS 9.2.1
(except iCloud Drive, and the new notes). Does not support iOS 10 or iTunes 12.5.1 according to the Wikipedia below.
Mac OS X 10.9.5 (Mavericks) one user has said is required for iOS 10 and iTunes 12.5. It is though unable to sync with iOS 11.
Mac OS X 10.10 (Yosemite) is required minimum for the new iCloud Drive and iOS 11 (except for Notes, which requires El Capitan). iTunes 18.104.22.168 is needed for iOS 11.
iTunes 12.8 is now available for 10.10.5 and later.
Mac OS X 10.11 (El Capitan) is required for the new Notes on iOS 9.
Mac OS 10.12 (Sierra) currently has no special requirements as of September 23, 2017
iOS 12 is slated for release September 17, 2018. Please make sure to backup your data on your iphone, ipad, or ipod touch and not apply any update until you are certain that iTunes on your Mac or PC can handle it.
Some may find running Windows on their Mac Running Windows on a Mac, and Connecting it to Mac
or creating a separate partition for a newer Mac OS How to format a drive, or disc for maximum portability?
allows one to sync to a newer iOS without losing compatibility of older Mac OS versions.
Stuck in Mavericks, Mac OS X 10.9.5? Now for the first time, there is a published way to downgrade your iOS.
Note: this is not for the faint at heart, but sure is better than having to upgrade your Mac OS X prematurely for an App you can't afford upgrading on your Mac.
The last iOS supported for various iDevices is listed on the table called "Terminal update for" on:
And many of the latest iOS versions and iTunes support are on https://en.wikipedia.org/wiki/History_of_iTunes
This tip will be revised as new info becomes available.