iPA Explains: Why Installing Big Apps & Games Requires Lots Of Extra Space
I’m guessing that many of you have run into the dreaded “not enough free space” message once while installing apps onto your iPhone even though the app should be small enough to fit. So why does the message appear? The truth is that, even though an app may report that it’s small enough to squeeze into the last few gigabytes on your iPhone, every app is compressed before it’s downloaded. This means that an app is transferred to your phone, uncompressed, and then the compressed version is discarded, effectively requiring a little more than twice the space of the reported size of the app.
So how much space does a large app need in order to be installed?Well the first thing you need to consider, especially with larger apps and games, is that once uncompressed, these apps are slightly larger than iTunes will report them as. A good example is the TomTom app. iTunes reports it as taking 1.21 GB but once uncompressed, it’s actually closer to 1.33 GB. This means that you’d need at least 2.54 GB free to install the app. You may even need to free up a little more.
The quickest way to squeeze one of those big apps into your iPhone or iPod touch is to temporarily dump off some music. Music doesn’t require zipping and unzipping to get on the phone, so you can put it right back after you’ve installed the app. To be safe, you’ll want to free up about 2.25x the amount of space that the app is reported to take up in iTunes. This method should allow you to fill every last bit of space without too much work.