How to merge iPhoto and Photo libraries on a Mac

A reader has enormous photo libraries, and wants to merge and trim them while archiving parts.

apple photos laptop stock
Credit: Apple

Christoph Stork’s photo libraries are overflowing. He owns a MacBook Pro with a 750GB drive, but has an iPhoto library that weighs in at 190GB and a Photos library that takes up 250GB. His drive is almost full and he’s not sure how to proceed.

How can I know whether the pictures in the iPhoto library are also in the Photos library? How can I move a portion of the older images away while keeping the last few years on the laptop?

If you followed the steps to import your iPhoto library into Photos whenever you started using Photos, all of the library’s full-resolution images weren’t duplicated. Instead, Apple chose to use “hard linking,” which Jason Snell explained back in April 2015. Instead of creating a copy of the iPhoto media, hard links just allow the same file to be linked in two or more places. Unlike an alias, which has a special icon and just points to another file, the hard link reference looks and acts exactly like it is a file.

This means that, in this case, the 190GB and 250GB iPhoto and Photos library likely contain a whole lot of overlap. Thumbnails, modified images, and other internal data structures aren’t duplicated from iPhoto, and take up separate space in each library. New images imported into Photos would explain its larger size.

My suggestion for proceeding in this and similar cases is to get an external 1TB (or larger) USB 3.0 drive, which are relatively cheap. Copy the iPhoto library there before deleting it. (Deleting a file that’s hard linked in other places only deletes a reference; the original file remains in place for its other uses, so don’t worry about that.)

For as long as older versions of iPhoto continue to work, you can open any library on a mounted volume by holding down Option at launch, and then navigating to the library and selecting it. The same is true for Photos, although Photos continues to be updated, and should work across many, many future macOS releases.

If you want to archive part of your Photos library, get PowerPhotos ($30), a third-party app that has a lot of features missing in Photos. It will let you create a new library and copy images over, rather than using an awkward export method.

To find just older images, I suggest creating a Smart Album with the criteria for the date range you want, and then selecting all the images in the Smart Album and creating a regular album from it. You can then use PowerPhotos to create a new Photos library, copy that regular album and all its contents to the new library, and delete the album and associated media from your main Photos library.

PowerPhotos includes a license for iPhoto Library Manager, which has similar features. Both apps can identify duplicates within a library to reduce a library’s size if you have many images that were imported multiple times or duplicated internally.

I highly recommend making more than one backup of the photos and libraries you migrate off your main drive. It can be cheap to store data you don’t plan to modify at Amazon S3, or you can use Google Drive, iCloud Drive, or other options.

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