The fastest way to see how much space you have left

Open the Apple menu in the top-left corner of your screen and select About This Mac. Click the Storage tab. You will see a bar showing your total disk capacity and how much is used, broken down by category: Apps, Documents, Photos, Backups, and Other. This tells you immediately whether you have room to work or whether your drive is nearly full.

If you want more detail than this overview provides — which you will if your drive is nearly full — you need a second tool. The Storage tab shows categories but not which individual files or folders are taking up space. That requires opening Finder and checking folder sizes yourself, or using a third-party app designed to show you what is consuming your disk.

Key Takeaways

  • The Storage tab in About This Mac shows your total capacity and how much space is used, updated in real time.
  • The Storage tab groups files by type but does not show you which specific files or folders are largest.
  • You can manually check folder sizes by right-clicking any folder in Finder and selecting Get Info, though this is slow for large directories.
  • Third-party apps like DiskSight, OmniDiskSweeper, or Disk Diag show a visual map of what is using your space and are faster than checking folders one by one.

Using Finder to check individual folder sizes

If you want to know whether a specific folder is taking up space — your Downloads folder, your Documents folder, or a project directory — you can check it directly in Finder. Open Finder, navigate to the folder you want to check, right-click it, and select Get Info. A window will open showing the folder size at the top.

This method works for any single folder, but it is slow if you need to check many folders or if you want to find the largest items on your entire drive. Finder will also take several seconds to calculate the size of very large folders. For a quick check of one or two folders you suspect are large, this is the simplest approach. For a full picture of what is consuming your disk, a dedicated app is faster.

Understanding what the Storage categories mean

Apps shows the size of all installed applications in your Applications folder. Documents includes files in your Documents folder plus other user files. Photos is your Photos library. Backups refers to local snapshots and Time Machine backups stored on your Mac itself (not backups stored on an external drive). Other is everything else: system files, caches, temporary files, and anything that does not fit the other categories.

The "Other" category often grows large over time because it includes system caches, browser caches, old installer files, and temporary data from apps. If your drive is full and "Other" is taking up significant space, that is usually where you can reclaim room. You can empty the Trash, clear browser caches, and delete old downloads — all of which fall into "Other" — without affecting how your Mac runs.

When your drive is almost full and you need space now

If your Mac is running slowly or you are getting warnings that your disk is full, start with the easiest wins. Empty your Trash by right-clicking the Trash icon in the Dock and selecting Empty Trash. Check your Downloads folder — it often contains old installers and files you no longer need. Delete old backups or Time Machine snapshots if you have them stored locally.

Next, look at what is in your Documents and Desktop folders. Large video files, old project folders, or duplicate files often hide there. If you use cloud storage like iCloud Drive or Google Drive, you can move files there and remove them from your Mac to free up local space. Be cautious about deleting anything from the System folder or Library folder — those are part of macOS itself and deleting from them can break your Mac.

Third-party apps that show disk space visually

DiskSight (paid, around $10) shows a treemap visualization of your entire disk, where each rectangle represents a file or folder sized proportionally to how much space it uses. You can click any rectangle to drill down and see what is inside. OmniDiskSweeper (free) works similarly and shows a list view of folders sorted by size. Disk Diag (paid, around $10) includes disk space visualization plus health monitoring for your drive.

All three are faster than manually checking folders in Finder, especially if your drive is large or you have many nested folders. They show you at a glance which folders and files are consuming the most space, making it easy to decide what to delete or move. If you regularly need to manage disk space, one of these apps saves time. If you only need to check space occasionally, the built-in Storage tab and Finder are sufficient.

How to prevent your disk from filling up

Check your storage regularly — once a month is reasonable. Open About This Mac and look at the Storage tab. If you are consistently above 80 percent capacity, start moving or deleting files before you run out of room. A nearly full disk slows down your Mac because the system needs free space to write temporary files and caches.

Set up Time Machine backups to an external drive rather than storing them on your Mac. Move large files like videos, photos, or archived projects to external storage or cloud services. Empty your Trash regularly instead of letting it accumulate. Clear your browser cache periodically — most browsers have a setting to do this automatically when you quit. These habits keep your disk from filling up unexpectedly.

Frequently Asked Questions

Why does my Mac say it is out of space when the Storage tab shows I have room left?

This usually means a single large file or folder is taking up more space than the remaining free space. Your Mac needs contiguous free space to write certain files. Check your Downloads, Documents, and Desktop folders for large video files or old backups. Moving or deleting one large file often frees up enough room to resolve the warning.

Is it safe to delete files from the "Other" category?

Some files in "Other" are safe to delete — old downloads, browser caches, and Trash contents. Others, like system caches and temporary files, should be left alone. Do not delete anything from /Library or /System folders. If you use a third-party app like OmniDiskSweeper, it will show you what is in "Other" so you can decide what is safe to remove.

What is the difference between storage and memory on my Mac?

Storage is your hard drive or SSD — the space where files, apps, and your operating system live. Memory (RAM) is temporary working space your Mac uses while running apps. The Storage tab shows disk space. If you want to check memory, open About This Mac and look at the Memory line. They are separate and both matter for performance.

Can I move my Photos library to free up space?

Yes. Open Photos, go to Settings (or Preferences on older Macs), click the General tab, and look for the library location. You can move your library to an external drive or cloud storage. Close Photos first, then drag your Photos library folder to the new location, and tell Photos where to find it. This frees up significant space if you have a large photo collection.

How much free space should I keep on my Mac?

Keep at least 10 to 15 percent of your total disk capacity free. If your drive is 500 GB, that means keeping at least 50 to 75 GB free. This gives your Mac room to write temporary files, run updates, and maintain performance. If you regularly work with large video or photo files, aim for 20 percent free space instead.