I’m trying to free up space on my Mac, but my photo situation is kind of out of control.
Over the years, I’ve ended up with a lot of random photo copies on my Mac—stuff saved from chats, quick edits, downloads, etc. The thing is, I already have a clean and complete photo library stored on an external SSD, which is where I want everything to live long-term.
Right now I basically want to clean my Mac by removing anything that already exists on that external drive. The tricky part is making sure I don’t delete something that isn’t actually backed up there.
Is there a practical way to compare files between my Mac and an external drive and safely remove duplicates from just one side?
If you want to do this safely, start small instead of scanning everything at once. Pick one folder on your Mac (like Downloads), then open the matching folder or year on your external drive side by side. Sort both by file size and date—duplicates usually line up pretty clearly that way. Once you confirm a pattern, you can delete in batches instead of checking one by one.
Before deleting anything, you can use Finder’s “Get Info” or Quick Look (space bar) to compare files quickly. If file size and resolution match exactly, it’s usually safe to assume they’re duplicates. Also, consider moving suspected duplicates into a temporary folder first instead of deleting right away—gives you a safety net in case something goes wrong.
I had almost the same setup—main archive on an external drive and a messy internal drive. Doing it manually got old really fast. I ended up using iBoysoft Cleaner to scan both drives together, and it grouped matching files so I could review them in one place. I still double-checked before deleting, but it saved a ton of time compared to comparing folders manually.