How to Find What Is Taking Up Space on a Mac

A disk fills up and macOS says “Macintosh HD — 27 GB available”. Which is true, and no help at all: it does not say where the other 467 GB went, and the usual answer is to install a cleaner app that scans the whole machine and offers to fix things you cannot see.

Storage answers the question in the file manager you already have open. It is in the ComfortFiles sidebar under Quick Access.

Choose what to look at

Three buttons sit under the ring: Home folder, Whole disk, and one for every drive you have plugged in.

Before you scan anything it already shows how full that disk is, and what a previous scan found there. Press Scan and it starts measuring.

What the ring says

The ring is where the space went, folder by folder, biggest first — the five largest with their sizes and everything else gathered into one line. It fills in as the scan runs rather than making you wait for a total.

What the list says

Beside the ring is what is actually worth a decision, grouped:

• Large files and Large folders — the biggest single things, wherever they are.
• App caches — what apps have stored to save downloading it again. Safe to remove; the app rebuilds what it needs.
• App leftovers — folders belonging to apps that are no longer installed.
• Old downloads — things in Downloads you have not opened in a long time.
• Duplicates — the same file, byte for byte, in more than one place.
• Photo & video libraries — a Photos, iMovie, Final Cut, Logic or GarageBand library is one item to macOS, so it is listed as one thing. The way to reclaim room inside one is to open the app and remove what you no longer want.
• Trash — everything in it, including the separate trash every external drive keeps. This is the one group listed in full rather than filtered by size, because the button beside it empties all of it.

Click a group to show only it, and click it again to see everything.

Nothing happens until you decide

A scan reads. It does not move, rename or remove anything.

When you do decide, ComfortFiles asks first — one file or twenty. The question names what it is about to take, adds up what it frees, and says how to undo it. That is not how deleting works in an ordinary folder, where a file goes quietly to the Trash and ⌘Z brings it back; here you are deciding about files you have never seen, with names like com.spotify.client, and a question is worth the two seconds.

Then the files go to the Trash — so ⌘Z undoes it immediately, and nothing is really gone until you empty the Trash yourself. There is no button that removes everything at once, because “everything” is not a category anybody can define for your files but you.

The Trash group is the exception, and only because the work is already done: what is in there was deleted a while ago and is still taking up room. Its button is Empty the Trash…, it asks the way macOS asks, and there is no ⌘Z afterwards.

Good to know

• A scan of a large disk takes minutes. It shows what it has found so far as it goes, and you can leave it running and come back.
• You can stop it. Cancel puts the panel back where the scan started; nothing is half-done.
• Some places cannot be read. The system volume is sealed and other accounts are private. Where a folder was refused, the panel says so instead of quietly counting it as zero.
• The numbers are what the files take on disk, not what they claim to be. A 4 MB file with no blocks allocated to it frees nothing, and it is not offered as if it would.

Frequently asked questions

How do I see what is using space on my Mac?

Click Storage under Quick Access in the ComfortFiles sidebar, choose what to look at — your home folder, the whole disk, or an attached drive — and press Scan. The ring shows where the space went, folder by folder, and the list beside it groups what is worth a decision: large files and folders, app caches, leftovers from apps you removed, downloads you have not touched in a year, and duplicate files.

Does it delete anything on its own?

No. A scan reads; it never moves or removes a thing. Anything you do decide to remove is confirmed first — one file or twenty. Everything you decide to remove goes to the Trash, so ⌘Z brings it straight back and the Trash holds it until you empty it. There is no “clean up everything” button, because nobody can know what your files are worth except you.

Is this a Mac cleaner app?

No, and deliberately not. Cleaner apps sell urgency — a scan that finds thousands of “issues” and one button that removes them. This shows you where your space went and hands the decisions to you, one list at a time, inside the file manager you already have open.

How does it find duplicate files?

By content, not by name: files of the same size are compared by a fingerprint of their first 64 KB and then, only if that matches, by a fingerprint of the whole file. Two files are called duplicates when they are byte for byte the same. It is limited to types where a duplicate is genuinely yours to delete — documents, images, video, audio, archives — and skips the insides of applications and app support folders, where a second copy is the program’s business rather than yours.

Why is the whole disk smaller than what my Mac says is used?

Because parts of a disk are not yours to read. macOS keeps its system on a sealed volume, other accounts’ folders are private, and Time Machine’s local snapshots take room that no folder can show. Storage counts what it can actually reach and does not invent the rest.

Can I look at an external drive?

Yes — every mounted drive gets its own button beside “Home folder” and “Whole disk”. A drive is scanned on its own terms, so what you see is that drive’s space rather than a slice of your Mac’s.