Update

It depends on what is the correct iOS version on your device and the internet speed.

However, it cannot be more than an hour.

Anita_51 Said:

"Update: How many minutes will it take to update to IOS 15.7.1"

-------

Update Using a Computer:

Have a Computer Handy? If so, try using a computer to update. Using a computer, you likely get a more reliable connection, and thus a faster install. See my user tip: Update your iPhone Using a Computer - User Tip