How to Reduce Your Photos Library Size on Mac

On many Macs, the Photos library is the single largest item on disk — years of high-resolution photos and 4K video stacked into one ~/Pictures/Photos Library.photoslibrary package. You can cut it down dramatically without deleting a single memory: let iCloud hold the originals, merge duplicates, and hunt the handful of videos doing most of the damage.

Check the damage first

Before changing anything, see what you're dealing with. In Finder, open your Pictures folder, select Photos Library, and press ⌘I — Get Info reports the package's full size. System Settings → General → Storage shows the same number under the Photos category. Anything from 50 GB up is normal for a long-running library; if it's crowding out everything else on your disk, the levers below are worth pulling in order.

Turn on Optimize Mac Storage

This is the biggest lever by far, and it's loss-free:

1. Open Photos, then Photos → Settings (⌘,) and click the iCloud tab.
2. Make sure iCloud Photos is turned on.
3. Select Optimize Mac Storage.

Full-resolution originals stay in iCloud while your Mac keeps lightweight versions, fetching the original whenever you open or export one. Space is reclaimed gradually as macOS needs it, not instantly — don't expect the storage bar to move the moment you flip the setting. The trade-offs: your iCloud plan must be big enough to hold the whole library, and you need an internet connection to pull originals, so keep full copies downloaded on at least one machine or backup you control. To undo, select Download Originals to this Mac in the same pane and the full library downloads again.

Merge duplicates

On macOS Ventura and later, Photos detects exact and near-identical shots for you. In the sidebar, open Utilities → Duplicates, then use Merge on each pair or Select All → Merge to sweep the lot. Merging keeps the highest-quality version and combines the relevant metadata — keywords, favorites, albums — so you lose nothing but the redundancy. It catches same-shot copies at different resolutions and formats too, which is exactly what years of re-imports and AirDrops leave behind. The discarded copies go to Recently Deleted, which is why the last step below matters.

Hunt the huge videos

Video, not photos, is usually where the gigabytes hide, and Photos gives you the tools to find it. In the sidebar, open Media Types → Videos, then select any clip and press ⌘I — the Info window shows its file size along with resolution and duration. Screen recordings, slow-motion clips, and long 4K captures are the classic offenders; a single ten-minute 4K video can outweigh a thousand photos. Delete what you'll never watch again. Remember that edits in Photos are non-destructive — the library keeps the original alongside the edited version — so trimming a long video inside Photos doesn't reclaim space the way deleting it does.

Empty Recently Deleted — the step people skip

Nothing you delete in Photos frees space immediately: items sit in Utilities → Recently Deleted for up to 30 days as a safety net, each showing how many days it has left. To reclaim the space now, open that album, unlock it with Touch ID or your password, and click Delete All — or select just the biggest items and delete those. Be sure first: this is the point of no return, and with iCloud Photos on, the deletion applies to every device signed into your account.

Library still too big?

If your library is healthy but your SSD simply isn't big enough, the clean escape is relocation: move the Photos library to an external drive and keep iCloud syncing exactly as before.