How to free up space on external hard drive

The transition from hard drives to solid state storage on both portable and desktop Macs has meant a significant reduction in storage space for most of us. That in turn has meant that many of us now have at least one external hard drive, SSD, or USB stick on which to store files. But those drives too quickly fill up and so it’s useful to know how to clean up an external hard drive. 

How you go about cleaning up depends on what you use the external drive for, so here’s our guide on how to free up space on an external hard drive.

Clearing space on a Time Machine hard drive

If you use an external hard drive for Time Machine and find that it’s running out of space, you may need to delete older backups. Time Machine will normally warn you when free space is low and offer to delete backups automatically.

If it doesn’t, you can do it yourself from within Time Machine, using Terminal, or by using an app like CleanMyMac X which has a module designed specifically for slimming down old Time Machine backups. Follow our guide on how to thin Time Machine snapshots.

Clearing space on an hard drive you use as an iTunes library

Many of us use external hard drives to house our precious digital music collections (with a backup on a second drive, hopefully). Like everything else, music libraries grow over time until they’re too big for the drive.

If you find yourself in that situation, don’t just drag files to the Trash, otherwise iTunes won’t know where they’ve gone and will behave very oddly next time you run it. Instead, launch iTunes, find the songs you no longer want, and delete them from within iTunes. That way iTunes library file will update and it won’t look for the files next time you use it.

If you sync an iOS device with iTunes, you can also free up space in an iTunes library by deleting old backups, apps, and other data. CleanMyMac X can help with that too. 

Clearing space on an external drive you use as a Photos library

Photos allows you to use an external drive to keep all your images, which is a great way to save space on your Mac. However, when the external drive starts to fill up, there is a clever way to create more space. 

  1. Launch Photos.
  2. Click on the Photos menu and choose Preferences.
  3. Select iCloud and make sure that iCloud Photos is checked – you might need to upgrade your iCloud storage plan to accommodate all your photos.
  4. Click the button labelled ‘Optimize Mac storage’. That will replace the full-resolution photos and videos in your Photos Library with smaller versions that take up less space. You can download the full-size versions any time. 

How to free up space on all your drives at once

Dragging files to the Trash is a very slow way to free up space on a hard drive. However, you can speed it up by identifying those files that will free up the most space the fastest — in other words, the files taking up the most space. By deleting them, perhaps after archiving them on another drive you don’t use on a day-to-day basis — you’ll quickly free up lots of space. 

You can identify the largest files on a drive manually by setting the Finder to list view and sorting files by size (click on the top of the Size column). However, you need to do that for every folder on the drive. Old files are another good candidate for deleting, or at least moving somewhere else. If you haven’t opened a file in six months or more, the chances are you won’t need it very often. You can use the same method to identify old files by sorting on Date Modified. Again, you’ll have to do it for every folder, so it could be time consuming. A much quicker way to identify and delete large and old files from your external hard drive or USB flash drive is to use a dedicated app like CleanMyMac X

Below are two ways of removing files from your drives: the easy way and the manual one. Choose the one you like!

Removing files with CleanMyMac X

CleanMyMac has a utility designed specifically to identify files that are occupying lots of space and those that haven’t been opened for a while. 

  1. Download CleanMyMac X and launch the app.
  2. Choose Large & Old files tab.
  3. Choose the disk and press Scan.
  4. You can go through files one at a time or click on the categories to the left of the list to filter them.
  5. When you find a file you want to delete, check the circle next to it.
  6. Click Remove.

Removing files manually

There is one more option, but it’s only for use in circumstances where you are absolutely sure you want to remove all the files on a drive. Instead of dragging them to the Trash and then emptying it, the best way to completely erase a drive is to use Disk Utility.

  1. Launch Disk Utility from Applications > Utilities.
  2. Click on the volume you want to erase in the left hand sidebar.
  3. Select the Erase tab.
  4. Give the volume a name and choose a format.
  5. If you want to securely erase the volume, select Security Options and choose them.
  6. Press Erase.


There are lots of options for freeing up space on an external hard drive, depending on what you use it for. If it’s a Time Machine backup or iTunes Library, you should do it from within those applications. Otherwise, one of the quickest ways to do it is to use CleanMyMac X to remove large and old files. That way you can reclaim the maximum amount of space for the minimum effort.

Thanks for reading and stay tuned!

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