How many iOS versions are available for the iMac?

Hello,

the iMac does not use iOS it uses MacOS. You can learn more about MacOS versions with this guide Find out which macOS your Mac is using - Apple Support.

-Drake

DannyBoy59 wrote:

how many iOS versions are available for the iMac?

None. Macs don't run iOS.

I lookup a Mac on https://everymac.com

and it can tell me (for example):

Pre-Installed MacOS: X     10.9.4 (13E28)       Maximum MacOS:      Current*

Then I do the math to see what versions are supported.

Macs will not run a version of macOS older than the version that came pre-installed. So in the above example Mac, the macOS versoins it supports are (using https://en.wikipedia.org/wiki/MacOS):

• 10.9 Mavericks
• 10.10 Yosemite
• 10.11 El Capitan
• 10.12 Sierra
• 10.13 High Sierra
• 10.14 Mojave
• 10.15 Catalina
• 11 Big Sur

You just have to figure out what iMac you have and its pre-installed macOS version, and you can then use the

https://en.wikipedia.org/wiki/MacOS

webpage to figure out what macOS versions your iMac supports.