Why is my iPhoto library larger than my Photos library?

My 2011 iMac died in 2018. That iMac had a built-in SSD and two 1 TB hard drives. The computer shop rescued the drives, and when I got a new iMac, I got new, larger external drives. Somewhere along all of this, I "upgraded" to Photos (against my will; I don't like Photos -- much prefer iPhoto). Now I'm going through my external drives to try to clean things up, and I notice that my iPhoto library is 232 GB, but my Photos library is only 48 GB. My iPhoto library stops in early 2018, when I got the new iMac, while my Photos library continues to the present. I checked and saw that the Photos library goes all the way back to the beginning of the iPhoto library; it appears nothing is missing. So I wonder: Why is the Photos library so much smaller than the iPhoto library, when it has more photos? Is Photos compressing my pictures?

iMac Line (2012 and Later)

Posted on Jun 1, 2021 12:45 AM

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Posted on Jun 1, 2021 12:55 AM

No, photos is not compressing your Pictures, but on sone System versions the size of the Photos Library is shown incorrectly in the Finder. Which System version are you using? The photos Library may really be larger than the iPhoto Library, if you gave iCloud Photos snd “optimize mac Storage” enabled in the Photos Preferences. Then the original image files may inly be stored in iCloud.

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Jun 1, 2021 12:55 AM in response to catservants

No, photos is not compressing your Pictures, but on sone System versions the size of the Photos Library is shown incorrectly in the Finder. Which System version are you using? The photos Library may really be larger than the iPhoto Library, if you gave iCloud Photos snd “optimize mac Storage” enabled in the Photos Preferences. Then the original image files may inly be stored in iCloud.

Jun 1, 2021 1:27 PM in response to catservants

It gets complicated with modern file systems.


The migrated library will be sharing the original files with the photos library via hard links - but both will be reporting the files size as though they "own"them. So in reality the migrated library will be taking very little extra space. This might be what has "Whatsize" confused. You could delete the migrated library - but if there were any files in there no longer compatible with photos, they won't have migrated, and deleting the migrated library will lose them.


If you ALSO have a copy of the original iPhoto library, not migrated, then most likely this is storing all the images - and will be taking additional space.

Jun 1, 2021 1:15 AM in response to léonie

I do not use iCloud Photos; I use Photo Stream, so "Optimize Mac Storage" does not apply (grayed out). You asked about which system version I am using -- not sure what you meant by that (macOS? 10.14), but that gave me an idea to look at the measurements in a different place. I was using WhatSize, which lists my Photos library at 48 GB, my iPhoto Library (which is on a different partition of the external drive) at 232 GB, and a third library called .migratedphotolibrary at 27 GB. After reading your response, I decided to check the Finder and see what it says. It lists my Photos library at 254 GB, my iPhoto library at 232 GB, and the .migratedphotolibrary at 232 GB. This makes more sense in terms of the number of pictures. I usually find WhatSize to list sizes accurately, so there must be something about the way iPhoto and Photos are structured for it to give different numbers than the Finder.


I'm trying to reorganize my external hard drives -- erase the partitions -- so I'm trying to figure out where to put things in the interim, and seeing Photos at 48 GB compared to iPhoto at 232 concerned me. I guess now my question is, how much space are these really taking up -- it appears they're not really taking up 718 GB, but maybe only what WhatSize is saying, 307 total. I'm thinking I can get rid of the .migratedphotolibrary library, and that keeping the iPhoto library isn't really adding 232 GB to my hard drive.

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Why is my iPhoto library larger than my Photos library?

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