You probably have gigabytes of wasted space in your iTunes library, and you don't even know it. Here's how to reclaim some of it

If you routinely download apps through iTunes, think twice about what you're doing. You probably have wasted a lot more space than you need to. Here's how to get some of that space back, and why it disappeared to begin with.

For me, it was just a bad habit that I started when I first started downloading apps from the App Store, years ago. I used to browse the App Store on my Mac through iTunes, then I'd download apps that I thought looked interesting, syncing my iPhone or iPod touch (and later the iPad) when the mood struck me.

For years it wasn't a problem - I had a large hard disk drive, storage wasn't an issue. What's more, my Mac was the hub of our household Home Sharing network, so my wife and kids would often copy new downloads from my iTunes library rather than having to retrieve a copy from the App Store themselves.

The fact is, though, Apple keeps track of what you download from the App Store. You can redownload those apps on any authorized device.

As a result, my Mac contained literally gigabytes of downloads I no longer needed - because those apps are available, whenever I need them, on demand through the App Store.

When I switched over to a Retina MacBook Pro, I suddenly found storage space at a premium - I had only a fraction available of what I had previously. At that point it made sense to delete the lion's share of the apps I'd downloaded. Many of those apps, large games especially, occupied hundreds of megabytes or a gigabyte or more. The net result is that I got literally dozens of GB back on my hard drive after I was done.

To delete apps you don't need anymore:

  1. Open iTunes
  2. Click the Apps icon in the Library sidebar.
  3. Select the apps you want to delete, and press the Delete key on your keyboard.
  4. When prompted, click the Move to Trash button.
  5. Don't forget to empty the trash once you're done.

Now, there are a few caveats. If you're a tightly metered Internet service, you may run into trouble if you have to download the same app onto multiple devices, because you're downloading the same data over the Internet multiple times.

What's more, if you're concerned about keeping an app that's been pulled from circulation - as some have, for various reasons - it may be wise to keep a local copy handy that you can restore if you need to.

You can also save space by deleting unneeded iOS device backups that iTunes has created. To do so:

  1. Go to the iTunes menu and click on Preferences.
  2. Click on the Devices icon at the top of the window.
  3. Select the backup you want to delete, and click the Delete Backup button.

How do you know if a backup is unnecessary? Some backups may have been sitting around for a long time. Take this one, for example. It's from when I last backed up my iPhone 5, the night before I bought my iPhone 5s.

I don't need that file any more. And as it turns out, I just got 1.8 GB of hard drive space by deleting it.

Delete unnecessary software updates

iTunes has a habit of spawning copies of firmware files for your iOS devices, which is helpful in the moment if you have to do a restore of your device. But once you've updated to the latest revision, having backups of previous firm updates is unnecessary, since the file is useless — Apple's firmware updates are "signed" with the servers to make sure that you can't downgrade your device.

The net result is that you may have gigabytes of wasted space on your hard drive for firmware files you'll never be able to use again. What's more, iTunes doesn't give you a way to manage these files - you have to go plumbing the old fashioned way, from the Finder. To check for these files, and to delete them:

  1. Go to the Finder and hold down the Option key on your keyboard.
  2. Select the Go menu and click on Library. (Library is ordinarily invisible to you from the Go menu unless you hold down the Option key)
  3. Find the iTunes folder.
  4. Look for the following folders: iPad Software Updates, iPhone Software Updates, and iPod Software Updates.
  5. If you find a file with a name that ends in "Restore.ipsw," drag it into the Trash.

It's safe to do this - if you need to restore your iOS device again, iTunes will go out to Apple's servers and download the latest firmware update necessary for your device.

What to do with your iOS device once you've cleaned up iTunes

Deleting apps from your iTunes library is fine, and you can get back sizable amounts of hard disk space that way - but what happens when you reconnect your iOS device to your Mac to back up?

You'll get a message that looks like this:

In short, iTunes is telling you that it's found software on your iPad that it can't reconcile with the contents of your iTunes library.

At this point, unless you have apps that have been pulled from the iTunes Store, it's safe to just click on the Don't Back Up Apps button. That way your Mac won't waste space backing up stuff you can just download again from the App Store if you need to.

Questions?

If you're like me and a constant grazer on the App Store, you can get back tons of hard drive space this way. Give it a try and tell me what you think in the comments!