What's Using Space

Open it from the More menu ••• → What's Using Space, or the What's Using Space tile on the Home screen. (Some screens call the same window the Storage Inspector — the menus use the plainer name.)

Make room… (top right) opens Emergency Space with a goal of 100 GB free — a plan, safest step first; nothing changes until you choose it. Review apps on the Applications row opens Apps on the apps still on this Mac, biggest first, where each can be moved or put away.

Everything here is measured on your Mac, not estimated. That's meant literally: where a figure can't be established, Storage Studio says so rather than filling the gap with a guess. Measure again walks your disk afresh, and results appear as they arrive instead of making you wait for the whole pass to finish.

What changed

The top section, and usually the one you came for. It compares this measurement against the previous one, over the exact window between the two readings:

• Gone — room taken by files that weren't there last time. Deleting

these gives the space back.

• Pinned — space held by your Mac's own recent backup snapshots of

files you've already deleted. Deleting more won't return it.

• Reclaimed — space released since the last reading, with nothing for

you to do.

The first time you open it there's no earlier reading to compare against, and it says exactly that rather than showing zeroes.

Biggest on this disk

Your largest folders, biggest first — and you can drill into any of them to any depth to find what's actually responsible, rather than stopping at a top-level folder that only tells you which room the mess is in.

Folders appear as each one finishes being measured, so the list fills in rather than blocking. Any row can be revealed in Finder, and Collapse all resets the view. A folder macOS won't let any app read is called out as unreadable, never silently counted as empty.

Space held by backups

How much room your Mac's local snapshots are holding — and how old it is. The heading gives you the headline immediately: how much is held, and how old the oldest snapshot is.

Each snapshot is listed with its age and when it was created, a plain description of why it exists (a restore point made before a system update, or a routine automatic one), and what can be done about it: required by macOS, your Mac can clear this by itself, or not marked clearable.

One honest caveat: macOS reports a single combined figure for all local snapshots and no size for any individual one. Storage Studio shows the combined total and says so, rather than dividing it up into numbers it would be making up.

A button alongside opens the Local Snapshots manager if you want to review or release them now.

iPhone and iPad backups that Finder keeps on your Mac are listed here too, and with your fast drive connected they can be moved there with Move to fast drive…. Storage Studio copies them, checks that every file arrived, and only then frees the space on your Mac; Finder carries on backing up to the drive, so keep it connected when you back up a device. Move back… brings them home any time, checked the same way. Neither runs while a device backup is in progress.

Known quick wins

Collapsed by default: the well-known caches and leftovers, with a count of how many are already empty — so a long list of nothing doesn't crowd out the real findings.

How much was covered

The footer never overstates its reach. If parts of your disk are off limits to any app, or measuring stopped early to stay out of your way, it says so and tells you what the figures do and don't include.

Emptying the Trash isn't offered here either. It's the one action that can't be undone, so it stays your decision.

Relocated

Relocated in the header opens the list of everything currently moved to your fast drive, each with a one-click Move back. This is where a move is undone — and it's worth being clear about what a move is: your folder keeps working because a link is left in its place, but the files themselves now live on the fast drive, so they're reachable while it's connected and not while it isn't.

When a copy is already on the fast drive

If a folder you move already has a copy on the fast drive, you choose what happens to it:

• Keep both (the default) — the drive's copy is renamed with today's

date, for example "Downloads (drive copy 27 Oct 2026)", and left exactly as it is. Your folder moves in beside it.

• Merge — the two are joined. A drive file with the same name but

different contents is renamed and kept, never overwritten; identical files are left alone. Nothing is deleted.

• Replace — the drive's copy is removed first. It doesn't go to the

Trash or the Recycle Vault, so you type Replace to confirm.