How long will it take to update my iphone 5 to ios 7?

So I'm currently updating my iphone 5 to ios 7. From my phone. It says 7 hours but that seems too long, how long does it take?

It depends. Today, a lot of users had trouble downloading it and many of them received error messages including me.
However, some had a very smooth downloading experience.

From what I've heard from my peers, those who didn't get an error message:
- 1 hour or even less to download the update
- 20 mins or so to update their phone.

MY Experience:
- I started at 1:00PM.
- I tried downloading multiple times from the minute iOS 7 was released worldwide.
- Had about 10+ error messages.

By the time I've finally downloaded the update (It's been 2 hours of repeatedly trying).
- 1 hour to download

By the time my phone has the update, I got another error message this time:
"Software update unavailable. Try again later."

So, I tried this multiple times and when I finally performed a hard reset, it worked.
- 15-20 minutes or so to update.

I finally got the update at 3:56 PM. (It took me a total of around 3 hours because of the error messages)

HOPEFULLY, now that the servers had calmed down a bit, yours won't take as long.
But, it really depends. It shouldn't take that long as long as you don't get any error messages.