# How to see what is taking up space on your Mac

_Updated 2026-10-21_

> **Quick answer:** Storage settings only shows categories. To see folders, sort Finder by size, use `du` in Terminal, or use a visualizer that draws your disk as a map of blocks.


## 1. System Settings → General → Storage

It shows the bar of categories (Applications, Documents, Developer, macOS, System Data and so on) and Apple's recommendations. It is the right first look, but it cannot tell you which folders sit inside System Data.


## 2. Finder, sorted by size

Open a folder in list view, choose **View → Show View Options** and tick **Calculate all sizes**, then sort by **Size**. Press **Shift-Command-.** to show hidden folders such as `~/Library`. It needs no tools but is slow for big folders.


## 3. Terminal with du

```
du -hd 1 ~ | sort -h | tail -15
du -hd 1 ~/Library | sort -h | tail -15
```

`-h` prints readable sizes and `-d 1` goes one level deep. Run it again inside whichever folder is biggest. Folders protected by macOS print `Operation not permitted`. Note that `du` reports the space really used on disk, which is why it can disagree with sizes that Finder lists, as in the [Docker.raw example](/guides/docker-raw-too-big-mac/).


## 4. ncdu, a browser inside Terminal

```
brew install ncdu
ncdu ~
```

ncdu is free and fast. You move through folders with the arrow keys and see the biggest ones first. To read protected folders it may need Full Disk Access for your Terminal app.


## 5. Visualizer apps

Visualizers draw your disk as a picture so the biggest things stand out at once. Prices and features change, so check each page before you decide:

| App | Style | Cost |
|---|---|---|
| DaisyDisk | Radial (sunburst) map | Paid |
| GrandPerspective | Treemap | Free, open source |
| Disk Inventory X | Treemap | Free |
| OmniDiskSweeper | List, biggest first | Free |
| See Your Disk | Treemap coloured like macOS Storage categories, with cleanup suggestions | App Store edition with in-app purchase, open-source edition free |

**How to read a treemap:** each rectangle is a folder, its area is its size, rectangles inside it are its subfolders, and colour marks the kind of data. Click a block to look inside, and bigger means more space.


## Which one should you use

- Want a quick look at categories: Storage settings.
- Want exact numbers for one folder: Terminal `du`.
- Want to browse everything and spot surprises: a visualizer.
- Want to find and clean what macOS calls System Data: a visualizer that marks what is safe to remove, such as [See Your Disk](/).


## Why tools disagree

- Some report apparent size and some report the space used on disk (sparse files such as Docker.raw).
- APFS clones share space, so adding files up can overcount.
- Snapshots and [purgeable space](/guides/what-is-purgeable-space-on-mac/) are counted by macOS but cannot be browsed.
- macOS Settings counts in GB (1000³) while `df` counts in GiB (1024³).

To then find out what is behind System Data itself, follow the [Terminal audit](/guides/find-whats-inside-system-data-mac/).

Get See Your Disk: [Mac App Store](https://apps.apple.com/us/app/clean-systemdata-seeyourdisk/id6817565741) · [GitHub](https://github.com/bikmeev/see-your-disk)

## Frequently asked questions

**Why can I not see System Data in Finder?**
System Data is a category in Storage settings, not a folder. It is the total of many places, such as caches, logs and app data, so there is nothing to open. A disk visualizer or a few Terminal commands show what it is made of.

**Do disk tools need Full Disk Access?**
Apps from the Mac App Store run in a sandbox and see the folders you grant. Tools that run outside the sandbox, including Terminal commands, need Full Disk Access to read protected places such as Mail and Safari data.

**What is the fastest way to find the biggest folders?**
In Terminal, `du -hd 1 ~ | sort -h | tail -15` lists the biggest folders in your home folder. A visualizer app shows the same thing as a map and lets you click deeper.

**Is scanning my disk safe?**
Yes. Scanning only reads names and sizes. Nothing is changed unless you choose to delete something.

## Related guides

- [What is inside System Data on Mac: a Terminal audit](https://seeyourdisk.com/guides/find-whats-inside-system-data-mac/)
- [What is System Data on Mac, and why is it so big?](https://seeyourdisk.com/guides/what-is-system-data-on-mac/)
- [How See Your Disk cleans: methods and safety levels](https://seeyourdisk.com/guides/how-see-your-disk-cleans/)