Mac Inside & Out · Activity Monitor & Storage · Lesson 3 of 5

Managing Storage on a Mac

Find what is filling your Mac, and free up space safely.

Where your space went

Your Mac keeps everything on its storage. Storage is the built-in drive that holds your apps, photos and files. When it is nearly full, the Mac can slow down, and updates may not install.

To check it, click the Apple menu, then System Settings. Choose General, then Storage. On older versions of macOS, look under About This Mac instead.

A colored bar shows what is using space, like Apps, Photos and Documents. Below it is a list of the same groups. Click the small Info button (an "i") next to one to see its biggest files. You can delete ones you no longer need.

Near the top, the Mac shows Recommendations. These are shortcuts that free up space for you:

• Store in iCloud: moves your Desktop and Documents files, photos and messages to iCloud. When space runs low, the Mac keeps only the files you opened recently. The rest wait in iCloud until you need them.
• Optimize Storage: removes Apple TV movies and shows you already watched. It also keeps only recent email attachments on the Mac.
• Empty Trash Automatically: erases items that have been in the Trash for more than 30 days.

iCloud is Apple's online storage. It only holds as much as your iCloud plan allows, so a big photo library may need a paid plan.

On Windows, the same tools live in Settings under Storage.

Trash, downloads and System Data

A few habits free up the most space.

Empty the Trash. Files in the Trash still take up space. Right-click the Trash in the Dock and choose Empty Trash. After that, the files are gone for normal use, so look inside first. On Windows, this is the Recycle Bin.

Clean out Downloads. Your Downloads folder slowly fills with installers, old PDFs and big videos. Open it in Finder and switch to list view. Click the Size column title to put the biggest files first. An installer file, often ending in ".dmg", can usually go once the app is installed.

Understand System Data. In the Storage bar, you may see a gray part called System Data. On older versions it was called Other. It holds files that don't fit the other groups, like caches and logs. A cache is a stash of temporary files that helps apps load faster.

System Data grows and shrinks on its own. It is not a folder you can open and empty, and macOS manages most of it for you. Don't buy "cleaner" apps that promise to shrink it. Some are scams, and some delete things you need. Deleting your own files that you no longer need is the safe way to make room.