Use Optimize Mac Storage with iCloud Drive to pack videos into a crowded Mac

iCloud can effectively give you up to 2TB of additional storage to supplement your Mac’s drive capacity, particularly useful with 256GB and 512GB Macs. The trick is using the Optimize Mac Storage checkbox found in the iCloud preference pane when you click Options to the right of iCloud Drive (Mojave and earlier) or in the Apple ID preference pane’s iCloud section at the main level (Catalina and later).

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Optimize Mac Storage lets you cram 50 lbs. of digital potatoes in a 5 lb. sack.

iCloud Photos and iCloud Music Library are their own beasts—iCloud Photos has its own optimization controls, while iCloud Music Library’s availability and management of locally stored and iCloud-stored files depends on whether you have an iTunes Match or Apple Music subscription.

But for general storage, iCloud Drive and optimized storage can be truly useful. As you add material to iCloud Drive and you start to run up against a full drive on your Mac, macOS deletes the local copy of files and puts placeholders in their stead, while iCloud retains the files. Double-click or open a file from an app, and macOS automatically downloads it.

As an example, one Macworld reader has nearly 500GB of instructional videos on an external drive connected to her Mac, and about 250GB of storage remaining on her computer, but would like to consolidate it all. iCloud Drive coupled with storage optimization can be ideal for this in the right circumstances.

First examine requirements and capabilities:

  • Check that you have enough iCloud storage purchased. You likely have to upgrade to 500GB or 2TB of storage—50GB is not usually enough to be valuable offloading from your Mac.

  • Check your broadband plan. Are you charged for excess data usage or throttled to a lower speed each month against some baseline, and if so, how close to that limit are you? (Some ISPs have temporarily suspended limits due to the pandemic and the work-from-home shift.)

  • Consider your broadband speed. Do you have enough throughput to upload many gigabytes and download them on demand?

Next, follow these steps:

  1. Select Optimize Mac Storage in the appropriate preference pane for your version of macOS as noted above. (If you have multiple Macs logged into the same iCloud account, you will need to enable optimization on each of them to avoid filling their startup volume.)

  2. Copy a batch of tens of gigabytes of data from your external sources to iCloud Drive.

  3. Wait for the files to upload fully. You can check via to see if the files are available there as a check on completion.

  4. Copy another batch of files. As pressure increases on your Mac’s storage, macOS will—as noted above—start deleting the local copies. You should be able to monitor storage and watch that happen.

  5. Continue a batch at a time: copy, wait for upload, repeat.

Another option is to upload directly via the site, but Apple provides just a file-selection tool, and uploading via a browser can be fraught with interruptions and slowdowns.

To be extremely clear: Don’t delete any files! macOS and iCloud manage the process so you don’t have to.