The fastest way to check your disk space
Open the Apple menu in the top-left corner of your screen and click About This Mac. Click the Storage tab. You will see a colored bar showing how much space your drive is using, broken down by category — Photos, Apps, Documents, and so on. This tells you when ready whether your drive is nearly full or has room to spare.
That single screen is usually all you need. If you want to dig deeper — to find out which single app or folder is taking up the most space — the steps below show you how.
Key Takeaways
- The Storage tab in About This Mac shows your total drive space and what is using it, in one glance.
- A nearly full drive (over 90 percent used) will slow down your Mac and prevent updates from installing.
- Photos, backups, and old app installers are the most common space hogs on a typical Mac.
- You can see which individual apps or folders are largest by using Finder or the built-in Storage Management tool.
Understanding the Storage tab colors and what they mean
The colored bar in the Storage tab uses different colors for different types of files. Blue represents apps and system files. Green is photos and videos. Orange is documents and downloads. Gray is other files — backups, caches, language files, and things you cannot easily sort into a category. Red means your drive is full or nearly full.
The number next to each color tells you how many gigabytes that category is using. If one color takes up most of your bar, that is where you should look first when you need to free up space. For example, if green is huge, your photo library is the problem. If gray is large, old backups or cached files are likely taking room.
The total capacity of your drive appears at the top of the bar — usually 256 GB, 512 GB, 1 TB, or larger depending on which Mac you own. The available space (the white part of the bar) is what you have left to use.
When your drive is too full and what to do about it
If your available space drops below 10 percent of your total drive, your Mac will start to slow down noticeably. Updates will fail to install because they need temporary space to work. Backups will stop running. You should aim to keep at least 15 to 20 percent of your drive empty.
The fastest way to free up space is to delete old files you no longer need. Empty your Downloads folder — files sit there forever by default. Delete duplicate photos from your Photos app. Move old projects or archived documents to an external drive. Uninstall apps you no longer use by dragging them from Applications to Trash.
If you want to see exactly which folders are largest, use Finder. Open a new Finder window, click Macintosh HD (or your drive name) in the sidebar, then press Command+A to select all. Right-click and choose Get Info. Finder will calculate the total size of everything on your drive. You can then open individual folders and repeat this step to find the largest ones.
Using Storage Management for a guided cleanup
macOS includes a built-in tool called Storage Management that suggests files you can delete. Open About This Mac again, click the Storage tab, and click the Manage button. You will see four categories: Recommendations, Large and Old Files, Documents, and Trash.
Recommendations shows things like old language files, duplicate photos, and large old downloads that are safe to delete. Large and Old Files lists files over 100 MB that you have not opened in months — often installers or project files you can safely remove. Documents shows your largest folders so you can decide what to archive or delete. Trash shows what is in your trash bin; emptying it frees up space when ready.
Storage Management does not delete anything without your permission. It only shows you what is there and suggests what you might not need. You decide what goes.
Photos and video libraries take up the most space
If your green section (photos and video) is large, your Photos app library is the culprit. A single 4K video can be 1 to 2 GB. A year of photos from an iPhone can be 10 to 20 GB. If you have years of photos, your library can easily be 100 GB or more.
You have three options: delete photos and videos you do not want to keep, move your library to an external drive, or subscribe to iCloud+ so your full library lives in the cloud and only recent photos stay on your Mac. If you choose to delete, open the Photos app, select the photos you want to remove, and press Delete. Photos moves them to a Recently Deleted album where they stay for 30 days before permanent deletion, giving you time to change your mind.
Backups and system files you might not know about
The gray section (Other) often includes old backups, system caches, and temporary files. If gray is taking up significant space, your Mac has accumulated files it no longer needs. Some of these are safe to delete; others are not.
Time Machine backups on your Mac itself (not on an external drive) can grow very large. If you have an external Time Machine drive, you can delete the local backups. Open System Settings, click General, then Storage, then look for Backups. You can delete old backups from there. Do not delete system files or language files unless you are certain you do not use them — removing the wrong thing can cause problems.
If you are not sure what something is, leave it alone. The Storage Management tool is safer because it only suggests things that are genuinely safe to remove.
Checking space on an external drive
If you have an external hard drive or USB stick connected to your Mac, you can check its space the same way. Plug it in, open Finder, click the drive name in the sidebar, then go to the Apple menu and click About This Mac. The Storage tab will show all connected drives. Click the drive you want to check and you will see its space breakdown.
External drives fill up just like internal ones. If you use an external drive for backups or file storage, check it regularly. A full external drive cannot accept new backups, which defeats the purpose of having one.
Frequently Asked Questions
How much space should I keep free on my Mac?
Keep at least 15 to 20 percent of your drive empty. If your drive is 256 GB, that means 40 to 50 GB free. If you regularly work with large video or photo files, keep even more free — 30 percent if you can. A full drive slows down your Mac and prevents updates from installing.
Is it safe to delete files from the Other category?
Some files in Other are safe to delete; others are not. Use Storage Management to see what it recommends — those suggestions are safe. Avoid deleting system files, language files, or anything you do not recognize. When in doubt, leave it alone.
Can I move my Photos library to an external drive?
Yes. Open the Photos app, go to Photos in the menu bar, click Settings, then Library. Click Change and select an external drive. Your library will move there, freeing up space on your Mac. Your Mac must be connected to the drive to view your photos.
What happens if my drive gets completely full?
Your Mac will become very slow, apps may crash, and you will not be able to save new files or install updates. Delete files when ready to free up space. Start with your Trash bin, then old downloads, then duplicate photos. Aim to get at least 10 percent free as quickly as possible.
Does deleting files from Trash actually free up space?
Yes. Files in your Trash bin still take up space until you empty the trash. Right-click the Trash icon in your dock and click Empty Trash. The space is then truly freed up and available for new files.