How to free up space on a Mac (2026)

Start by finding out where the space went

Almost every "my Mac is full" article opens with a list of things to delete. That order is backwards. On a 512 GB drive the difference between the biggest folder and the tenth biggest is usually 40 GB or more, so an hour spent emptying Downloads can be worth less than two minutes spent on one forgotten virtual machine image. Measure first, delete second.

macOS gives you a rough answer in Apple menu → System Settings → General → Storage. It is a good sanity check for the total and almost useless for finding the cause: it groups everything it does not recognise into "System Data", which on a developer machine is routinely 100 GB and which the panel will not let you open.

What you want instead is a size-ranked view of the actual directory tree — each folder shown in proportion to the bytes underneath it, so the problem is visible rather than deduced. A disk space analyzer does exactly that. On macOS the well-known ones are DaisyDisk, GrandPerspective, OmniDiskSweeper, DiskBuddy and our own app.

You can also do it from the terminal with no installation at all. The command below prints the twenty largest items directly inside your home folder. It is read-only and safe to run.

du -h -d 1 ~ 2>/dev/null | sort -rh | head -20

du reports allocated blocks and cannot read folders macOS protects, so its total will not match Finder exactly. It is for ranking, not for accounting.

The eight places the space usually is

Across a lot of Macs the same directories come up again and again. In rough order of how much they tend to hold:

• ~/Library/Developer — Xcode. DerivedData, iOS simulator runtimes, device support and archives. Frequently 30–120 GB on a machine that has been building iOS apps for a year.
• ~/Library/Containers and ~/Library/Application Support — per-app data. Docker Desktop keeps its whole virtual disk in ~/Library/Containers/com.docker.docker; Slack, Notion, Discord and Figma each cache aggressively.
• ~/Library/Caches and /Library/Caches — regenerable caches. Individually small, collectively 5–30 GB.
• ~/Downloads — installers, disk images, exports. The single easiest win because almost everything in it is either already installed or re-downloadable.
• Photos and Music libraries — ~/Pictures/Photos Library.photoslibrary and ~/Music. Real data; manage from inside the apps, never in Finder.
• Time Machine local snapshots — invisible in Finder, reported by macOS as "purgeable". Covered in its own article.
• Mail — ~/Library/Mail. Downloaded attachments from years of threads.
• node_modules, target/, .venv, build/ — one project is 300 MB; forty projects are 12 GB.

The first pass: safe, fast, reversible

Do these in order. Everything here is either regenerable or something you explicitly chose to keep, and all of it can go to the Trash rather than being destroyed outright.

Empty the Trash first — it costs nothing and it makes every later number honest. Then sort Downloads by size in Finder (View → as List, then click the Size column) and delete the disk images and installers for software you have already installed; a .dmg you have already dragged into Applications has no further use.

Next, look at what iOS and Android development left behind if you do that work: Xcode DerivedData is entirely rebuildable, and unavailable simulator runtimes are dead weight. Both have their own article. Then check Docker, which does not shrink its disk image when you delete containers — you have to ask it to, from Docker Desktop → Settings → Resources, or with `docker system prune`.

Finally, look for single large files you had forgotten: video exports, virtual machine images (~/Virtual Machines, ~/Parallels), old project archives. One of these is often worth more than the entire rest of the list.

# What is in Downloads, largest first
du -h -d 1 ~/Downloads | sort -rh | head -20

# Docker reclaimable space (read-only)
docker system df

The second pass: things that need a decision

These are bigger and are not automatically safe. Read each one before acting.

iCloud Drive "Optimise Mac Storage" (System Settings → [your name] → iCloud → iCloud Drive) evicts local copies of files that are already in the cloud, leaving a placeholder. This frees a lot of space quickly, but the files then need a network connection to open. Turn it on if your connection is reliable; leave it off if you work offline.

Photos, if it is set to "Download Originals to this Mac", holds every full-resolution photo and video locally. Switching to "Optimise Mac Storage" inside Photos → Settings → iCloud can free tens of gigabytes and is fully reversible.

Old iOS device backups sit in ~/Library/Application Support/MobileSync/Backup and are often several gigabytes each. Delete them from Finder → your device → Manage Backups, not by hand — deleting the folder directly can leave the sync database inconsistent.

Mail attachments live under ~/Library/Mail. The supported way to shed them is Mail → Settings → Accounts → Account Information → Download Attachments: "None". Mail re-downloads what you open. Do not delete files inside that directory by hand.

Never delete anything under /System, /usr (except /usr/local), /bin, /sbin or /private/var/db. macOS protects most of it, and the parts it does not protect are still load-bearing.

What not to do

A few "tips" circulate that cost people data. Do not delete ~/Library wholesale, or any folder inside it whose purpose you cannot name — it holds your app preferences, mail, messages and keychain, not junk. Do not run `sudo rm -rf` against anything you have not read the contents of; there is no undo and there is no Trash. Do not delete files inside a .photoslibrary or .musiclibrary package; those are databases that break when you edit them from Finder.

Be sceptical of "cleaner" apps that offer to remove "system junk" without telling you which files. Any tool worth running shows you the full path list before it acts, and puts things in the Trash by default so a mistake is a drag away from being undone.

Keeping it from happening again

Disk pressure is a recurring condition, not a one-off event. Three habits do most of the work: set Finder → Settings → Advanced → "Remove items from the Trash after 30 days"; clear DerivedData and stale simulator runtimes after each major Xcode upgrade; and re-check the ranked view once a quarter rather than waiting for the "startup disk is almost full" dialog, which arrives when you have the least time to deal with it.

Dropit was built around that measure-first loop. Scanning your whole Mac and looking at it eight ways — treemap, sunburst, flame graph, bubbles, folder cards, top sizes, age map, mind map — is free and needs no account, and nothing about your files ever leaves the machine. The paid half is the part that acts: staging items for cleanup with a plain-English safety reason on each one, finding duplicates, uninstalling apps with their leftovers. If you would rather do everything above by hand, the free scan still tells you exactly where to point.