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How to free up disk space on your Mac

“Your startup disk is almost full” usually arrives at the worst moment — mid-update, mid-export, mid-download. Most of that space is genuinely reclaimable. This guide goes through it in order: measure first, take the easy gigabytes, then deal with duplicates, large files and app leftovers.

Updated 2026-08-02 · Written by the CleanerMac team · macOS 13–15 tested

First, find out where the space went

Deleting at random wastes time. Spend two minutes measuring first.

Open Apple menu → System Settings → General → Storage. The bar chart splits your disk into Applications, Documents, Photos, Mail, Messages, macOS and System Data. Click the info button beside any row to see the largest items inside it — the Documents row in particular gives you a sortable, deletable file list.

Terminal gives you exact numbers faster:

• df -h / — how much is actually free on the startup volume.
• du -sh ~/* 2>/dev/null — size of every folder in your home directory.
• du -sh -- ~/Library/Caches/* — per-app cache sizes, sorted by eye.
• du -sh ~/Library/Developer/Xcode/DerivedData — for developers, frequently the biggest single folder.

If the Storage screen shows an enormous System Data block, read the System Data guide — it is a catch-all bucket for caches, swap, local Time Machine snapshots and unclassifiable files, not a folder you can open.

Quick wins: the first few GB

1. Empty the Trash. Files there still occupy the disk. Right-click the Trash → Empty Trash. Photos and Mail keep their own Recently Deleted areas — empty those separately.
2. Clean out Downloads. Open it in Finder, switch to list view, sort by Size. Old .dmg, .pkg and .zip installers are pure waste once the app is installed.
3. Delete old iOS device backups. They live in ~/Library/Application Support/MobileSync/Backup and are often several GB each. Remove them from Finder's device sidebar, or delete the folders directly if the device is long gone.
4. Clear caches. ⇧⌘G → ~/Library/Caches. Quit an app before clearing its folder, then delete the contents. Also check ~/Library/Logs. Step-by-step in how to clear cache on Mac, and browsers specifically in clear Safari cache.
5. Empty Xcode's DerivedData if you develop: quit Xcode, then drag ~/Library/Developer/Xcode/DerivedData to the Trash (⇧⌘G to reach it). Xcode rebuilds it on the next build. See the DerivedData guide.

Together these often free several GB on a Mac that has been in use for a year or more, and none of them risks anything irreplaceable.

Turn on the built-in storage tools

macOS ships four recommendations on the Storage screen. They are genuinely useful, with one caveat each.

• Store in iCloud — moves the full-resolution originals of Desktop, Documents and Photos to iCloud, keeping thumbnails locally. Caveat: it consumes iCloud storage, so you may be trading disk space for a monthly bill, and files need a connection to open.
• Optimise Storage — removes watched Apple TV purchases and old email attachments. Caveat: attachments re-download when you open them, which is slow on a poor connection.
• Empty Trash Automatically — deletes items after 30 days. Caveat: it is a real deletion, so treat the Trash as temporary from then on.
• Review the Documents category — click its info button for Large Files, Downloads, Unsupported Apps and a File Browser view of your home folder. This is the most immediately useful of the four.

The bigger targets: duplicates, large files, app leftovers

Once the easy gigabytes are gone, three categories usually hold the rest.

Large forgotten files. In Finder press ⌘F, set the scope to This Mac, then change the first criterion to File Size — is greater than — 500 MB. Add a second criterion for Last opened date — is before — a year ago. What surfaces is usually old video exports, virtual machine images, and disk images you forgot to delete. More approaches in find large files on Mac.

Duplicates. The same photo imported twice, a document copied to a second folder, an entire project folder duplicated as a manual backup. Finding them by name fails because copies get renamed; you need content matching. The duplicate files guide shows both a Terminal method with shasum and the faster route, and duplicate photos covers image libraries specifically.

App leftovers. Every app you ever dragged to the Trash probably left data behind in ~/Library/Application Support, ~/Library/Containers, ~/Library/Group Containers, ~/Library/Preferences and ~/Library/Saved Application State. Some of those folders are hundreds of megabytes. Read how to uninstall apps properly before you start deleting Library folders by guesswork.

Doing all of it in one pass

Everything above is free and works. It also takes the better part of an hour and requires you to be careful in a folder where mistakes matter. That is the case for a tool: CleanerMac maps your disk by category, matches duplicates by SHA-256 content hash so renamed copies are caught, ties leftovers to the app's bundle identifier rather than its name, and skips the cache of any app that is currently open. Duplicates, large files and app leftovers go to the Trash, so those are recoverable; rebuildable caches and build folders are deleted outright.

It is a native menu-bar app for macOS 13 and later, runs entirely on-device with no account or upload, ships in 20 languages, and costs $24.99 once with a 3-day free trial. Use it or use the manual steps — the steps above are complete either way.

The categories most people forget

After the obvious folders, these five hold more space than almost anyone expects.

• Mail attachments. Mail downloads every attachment you have ever received into ~/Library/Mail. On an account with years of history this can be several GB. In Mail → Settings → Accounts → Account Information, set Download Attachments to Recent or None for IMAP accounts, since the server keeps the originals.
• Messages. Photos and videos sent in iMessage are stored locally. In Messages → Settings → General, set Keep messages to one year, and check the attachment list in the conversation info panel.
• Old simulator runtimes and toolchains. Beyond DerivedData, Xcode stores device support files under ~/Library/Developer/Xcode/iOS DeviceSupport and simulator images under ~/Library/Developer/CoreSimulator/Devices. Use xcrun simctl delete unavailable to remove simulators tied to runtimes you no longer have.
• Docker and virtual machines. Container images and VM disk files are sparse files that grow and never shrink automatically. Run docker system prune -a, or delete VM images you no longer boot.
• Language files and unused printer drivers bundled inside apps. These are small individually and modern cleaners largely ignore them; do not spend time here until everything above is done.

Check each with du -sh before acting so you know whether the effort is worth it. A folder that turns out to be 80 MB is not where your disk went.

When the disk fills up again immediately

If you free space and it vanishes within days, one of these is usually responsible:

• Local Time Machine snapshots. macOS keeps hourly local snapshots when the backup drive is absent. List them with tmutil listlocalsnapshots /. They are purged automatically under disk pressure, so they are rarely a real problem, but they do inflate System Data.
• Photos or iCloud Drive re-downloading. If Optimise Storage is off, the full library syncs down again.
• An app writing runaway logs or caches. Re-run du -sh -- ~/Library/Caches/* a week later and compare — one folder growing by gigabytes points at the culprit.
• Docker, virtual machines or container images. These allocate large sparse disk files that grow and never shrink on their own.

And if the warning is already blocking your work right now, the startup disk full page covers the emergency version of this process. Once you have room again, a slow machine usually benefits from a tune-up pass too.

Get your gigabytes back

See exactly what filled your disk — then clear it in one pass.

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macOS 13+ · Apple Silicon & Intel · $24.99 once, no subscription