I have two "photos" libraries and only want one. How do I merge/consolidate them?

Photos has no tools to merge two libraries by importing one into the other.

• You can either export the photos from the smaller library and import them into the larger library,
• or merge the libraries in iCloud, if you sign up for enough iCloud storage to accommodate the merged libraries. To merge in iCloud enable one of your Photos Libraries as your iCloud Photo Library and wait for the photos to upload to iCloud, then switch to the second library , enable this as the iCloud Photo Library, wait again for the the photos to upload. iCloud will download the photos from the first library to the second, and you will have a merged library in the second library.

Or buy PowerPhotos. This tool allows to move selected photos between libraries and can help you to merge Photo Libraries. You can buy it here:

Powerphotos: Fat Cat Software

léonie- will merging in iCloud preserve all modifications in both libraries? If I download originals to the new System Library, will they be the same resolutions format (Raw, jpg) as the masters in the old System Library?

This sounds like it's a nice workaround for no way to locally merge libraries in Photos (I don't mind using iCloud and have plenty of storage thanks to the gap between 200GB and 1TB tiers) but it sounds too good to be true.

Thanks for the help.

Merging in iCloud will preserve your edits, your meta data, iCloud Photo Library will store the original files at the full resolution, and as a bonus weed out duplicate original files.

But it will not preserve projects (books, calendars), and and you will only see the faces thumbnails in the library where you created them, like described here: Use Photos and iCloud Photo Library on multiple Mac computers - Apple Support

Thanks for the info. I'm hoping this is a good option for "merging" my converted Aperture Library (now a Photos Lib) and my Photos Lib (which I created w/o realizing I couldn't merge 😟 ). This sounds like my best option, albeit with a little bit of cleanup afterwards.

It will depend on your network speed and the size of your libraries. Merging in iCloud requires uploading the complete libraries.

If that is not a problem, go ahead.