What is safe to delete on a Mac?

Most advice about freeing space on a Mac is a list of folders. Lists go out of date, and they cannot cover the app you installed last week. What carries over is the test behind the list, so start there.

Three questions to ask about any file

1. Does it come back on its own? A cache, a log or a build folder is made by software, and the software makes it again when it needs it. Deleting it costs nothing that matters.
2. What does it cost when it comes back? Some things regenerate but not for free: a simulator runtime is several gigabytes to download again, and a project’s node_modules means the project will not build until you reinstall it.
3. Is there another copy? Your photos, your documents, an iPhone backup and an app’s own database are not made by anything. If this is the only copy, it is not clutter however large it is — it belongs on another drive, not in the Trash.

If the answer to the first question is yes and the second is “nothing much”, delete it. If the answer to the third is no, do not.

Safe to delete: things that regenerate

• Application caches in ~/Library/Caches. Apps rebuild them as needed. Quit the apps first, because a cache an app is holding open can come straight back or leave the app confused until it restarts. The details are in how to clear the cache on a Mac.
• Your own logs in ~/Library/Logs. Only useful when you are chasing a bug.
• Browser caches. Temporary copies of pages and images. Your passwords, history and bookmarks are stored elsewhere and are not part of the cache.
• Package manager caches — npm, Yarn, Homebrew, CocoaPods, Gradle. Re-downloaded on the next install, which is slower once and then normal again.
• Xcode’s DerivedData. Rebuilt on the next build; close Xcode first. More in Xcode DerivedData.
• Mail Downloads. Copies of attachments you have opened. The originals stay in your mailbox.

These grow back, and that is expected. If space vanishes again within days, something is regenerating it, and a regular clean is the answer rather than a bigger one.

Worth a look first: things that cost something

• The Downloads folder. Mostly installers you have already run — but also the one PDF you were sent and never saved anywhere else. Look before you empty it.
• Simulator runtimes and old simulators, if you develop for iPhone. Removing one means downloading it again — see old simulator runtimes.
• Project build folders such as node_modules. Rebuildable, but the project will not run until you rebuild it.
• Message attachments. Deleting them leaves blank attachments in your conversations.
• Duplicate files. Genuinely wasted space — as long as one copy is kept, and you know which.
• Apps you no longer use. Uninstall them properly, so their support files go with them: uninstalling apps completely.

Yours: move it, do not delete it

• iPhone and iPad backups, unless the device also backs up to iCloud or you have a newer one.
• Xcode Archives. They may be App Store submissions, and their symbol files are what make a crash report readable.
• App containers in ~/Library/Containers. Each app’s documents and settings, not a cache.

For all of these, another drive frees exactly the same space and loses nothing.

Never delete these in Finder

• The Photos library. Deleting or moving it in Finder can lose photographs. Turn on Optimise Mac Storage in Photos’ iCloud settings instead.
• ~/Library/Application Support. For many apps this folder is the data, not a copy of it, and the folder is often not named after the app that owns it.
• /private/var/folders, macOS’s temporary data. Restart instead: macOS clears most of it at startup, safely.
• Anything under /System. macOS protects it anyway.

The pattern behind all four: the safe way to shrink them exists, and it is somewhere other than the Delete key.

Letting RefreshYourMac sort it for you

Doing all of this by hand means opening a dozen folders and judging each one. RefreshYourMac does the measuring and the sorting: it scans 45 categories on your own Mac, sizes each one, and rates it by the same three questions — at one of four safety levels.

• Safe to Remove — regenerates on its own. Application caches, Xcode DerivedData, the npm cache. These can be cleaned together in one go, after a confirmation.
• Review — costs a rebuild, a re-download or an app restart. Simulator runtimes, duplicates, project build folders. Cleaning shows a confirmation that says what it will cost.
• Move to Backup — your data. There is no bulk clean at this level at all: the button opens the list and you pick items one at a time, or move them to another drive.
• Protected — your Photos library, Application Support, macOS temp data. Measured and shown for their size, never deleted — each one points you at the safe way to shrink it.

The rating is not a label beside a button; it decides what the button is allowed to do. A Move to Backup category cannot be cleaned in bulk however hard you click, and a Protected one has no delete at all. The duplicate finders keep one copy of every file and never even list it, so cleaning everything on screen cannot remove the last copy of anything. And nothing is deleted without a confirmation.

Scanning is free, so the quickest way to find out what is safe to delete on your Mac is to let it measure. The reasoning behind each rating is in how it decides what is safe.