Every time you get an IOS updates, it says 117MB only , but when you download the darn thing, it  requires a big chunk of your phones memory and its sort of annoying. You rush to delete music, pictures or anything to get that new shinny update on your phone, but the questions is why does it require so much when its only a small update?

It’s actually for your protection. The Tech Block points out a great explanation from redditor StarManta: Apple is actually trying to make sure it doesn’t completely brick your phone. That megabyte file size is a compressed file downloaded onto your smartphone. However, your device also needs the requisite space to create temporary files while the update installs, in case something goes wrong. Only after the upgrade is a confirmed success is it safe to send the old files to the trash heap.

In StarManta’s words:

If you do it one file at a time and the process gets interrupted, you can end up with a half-applied update and completely bricked phone. On the other hand, if you store all the modified files until the last second, there is a much smaller chance of the process being interrupted at a crucial point, and he phone can more easily fall back to its previous functional state.

The best option for you to install the Update to any phone is to just connect it to Itunes and you should be able to install any update without using the phones memory at all. Don’t rely on your phone to do all the work, especially when its downloading on wifi. The computer and your phone are best friends in these kind of things and you will thank yourself when you download and update using a computer because it saves you time and phone space.