Optimize Mac Storage is on, but the Photos library is still huge: what it actually does
Optimize Mac Storage only shrinks your library when the Mac is short of space, and only for photos safely in iCloud. How to check it is working.
You turned on Optimize Mac Storage in Photos, waited a day, and the library is still 80 GB. It is probably working exactly as designed. It just does not work the way most people expect.
What it really does
- It does not shrink the library straight away.
- When your Mac runs short of space, macOS replaces full-size originals with smaller versions, oldest and least viewed first.
- It only does this for photos already uploaded to iCloud.
- If there is plenty of free space, it may keep most originals on the Mac.
Check it is set up right
- Open Photos, Settings, iCloud. iCloud Photos must be on, and Optimize Mac Storage selected.
- Check uploading is finished: at the bottom of the Library view, Photos shows the sync status. If it says it is uploading, originals cannot be removed yet.
- Check your iCloud storage is not full. If it is, uploads stop, and nothing can be optimized.
du -sh ~/Pictures/*.photoslibraryWhy it seems not to work
| Reason | What to do |
|---|---|
| Plenty of free space | Nothing, it will act when space is needed |
| Uploads not finished | Leave Photos open and on power until done |
| iCloud storage full | Upgrade the plan or free iCloud space |
| Library is not the System Photo Library | Only that library syncs. Set it in Photos, Settings, General |
| Most space is not originals | Analysis caches, see photos analysis cache |
If you need the space now
There is no button to force it. Getting the disk low triggers it, which is a poor way to work. The dependable alternative is moving the library to an external drive. Photos library taking up space covers both approaches, and iCloud storage full versus Mac storage explains how the two relate.
Common questions
Why is my Photos library still large with Optimize Mac Storage on?
Optimize only replaces originals with smaller versions when the Mac runs short of space, and only for photos already uploaded to iCloud. With free space available, it may keep most originals.
How do I force Optimize Mac Storage to free space?
There is no direct button. Make sure uploads have finished and iCloud has room. For space now, move the library to an external drive instead.
Does Optimize Mac Storage delete my photos?
No. Full-size originals stay in iCloud, and the Mac keeps smaller versions that download the original when you open them.