How To Check Storage On Mac

Tips
1

I’m starting to get warnings that my Mac is almost out of space, and some apps are running really slowly and crashing. I haven’t managed storage on a Mac before and I’m not sure where to see detailed info about what’s taking up room (system files, apps, photos, etc.). Can someone explain the steps to properly check storage on macOS and any built-in tools I should be using to understand and manage it?

2

First thing is to see what is filling the drive.

  1. Quick overview of storage
    • Click the Apple menu 
    • System Settings
    • General
    • Storage

Wait a bit. macOS scans stuff.
You get a bar showing Apps, Photos, System Data, etc.
Click the little “i” next to each section for more detail.

  1. Check big folders in Finder
    • Open Finder
    • In the top menu, Go > Home
    • Press Cmd + J and turn on “Show Path Bar” if it is off
    • Now go to each folder and sort by size:

    • Documents
    • Downloads
    • Movies
    • Pictures
    • Desktop

Easiest way:
• Right click a folder
• Get Info
• Wait for size to populate
Do this for big suspects like “Movies” and “Pictures”. Photos Library and iMovie Library often explode in size.

  1. Use “Manage” tools
    In that same Storage screen, hit “Manage”.
    Useful bits:
    • Applications
    Sort by size. Remove ones you do not use.
    • Documents
    Look at “Large Files” and “Downloads”.
    Delete old installers, DMGs, ISOs, ZIPs.
    • iOS/iPadOS backups
    Old iPhone backups eat tens of GBs.
    • Mail
    Attachments take space. If you use Mail a lot, check this.

Empty the Trash after deletes, or no space frees up.

  1. Check hidden Library stuff
    From Finder:
    • Go > Go to Folder
    • Type: ~/Library
    Inside, big folders often:
    • Application Support
    • Containers
    • Messages
    Sort columns by size in List view.
    Be careful here. Google each folder before deleting if you are unsure.

  2. Check “System Data” bloat
    System Data in the storage bar often holds:
    • Local Time Machine snapshots
    • Old logs
    • Cache files

Local snapshots:
Open Terminal, type:
tmutil listlocalsnapshots /
If there are tons and you use Time Machine to an external drive, you can delete old ones:
sudo tmutil deletelocalsnapshots
Only do this if you understand what Time Machine is doing.

Cache cleanup:
You can safely delete cache folders. They rebuild.
• Go to ~/Library/Caches
• Delete contents, not the Caches folder itself
Also /Library/Caches for system wide, though you need admin password.

  1. Check your Photos and iCloud settings
    Photos > Settings > iCloud
    If “Download Originals to this Mac” is on, your whole library sits local.
    Switch to “Optimize Mac Storage” if you use iCloud Photos and need more free space.
    Then let the Mac sit plugged in and on Wi Fi. It offloads some local copies.

  2. Check free space target
    For smooth performance on macOS, try to keep at least 10 to 20 percent of your disk free.
    Example, 512 GB SSD, try to keep 50 to 100 GB free.
    If you are down under 10 GB free, macOS struggles and apps crash more.

  3. If you want a more detailed view
    There are third party tools like DaisyDisk or GrandPerspective.
    They show a visual map of every folder and file.
    Run once, delete big junk, uninstall after if you do not want more apps staying around.

  4. Last step after cleanup
    • Empty Trash
    • Restart the Mac

Then go back to System Settings > General > Storage and recheck numbers.
If you still see weird usage, take a screenshot of the storage bar and list of largest folders and post it. That helps people point to the exact hog.

3

@reveurdenuit covered the built‑in tools really well, so I’ll throw in some extra angles and a few “gotchas” that catch people out.

  1. Use Finder’s search like a scalpel, not a hammer
    Instead of poking random folders:
  • Open Finder
  • Press Cmd + F
  • At the top, change “Kind” to “Other…”
  • Search for “File size” and select it
  • Now set it to “is greater than” and pick something like 1 GB

Scope it to “This Mac” or a specific folder (like your Home). This gives you a live list of the absolute monsters on your drive, regardless of where they are hiding.

You can also change the size filter to 500 MB or 100 MB and work your way down.

  1. Check external‑storage related space hogs
    If you use anything like:
  • Dropbox / Google Drive / OneDrive
  • Creative Cloud (Adobe)
  • Steam / game launchers

Each of these can silently sync or cache tons of stuff locally.

Examples to check in your Home folder:

  • “Dropbox” / “Google Drive” / “OneDrive” folders: right‑click > Get Info
  • “Movies” for game data (Steam puts big stuff into ~/Library/Application Support/Steam but you can at least see that it’s huge)

If you use Dropbox, right‑click large folders and set them to “Online-only” instead of “Local” to reclaim space without deleting.

  1. Look specifically for “orphan” DMGs and installers
    The Storage screen’s “Documents > Large Files” finds some of these, but it misses others.

In Finder search (Cmd + F):

  • Kind > Other > “File extension”
  • Look for: dmg, iso, zip, pkg
    Sort by size. Old app installers and disk images are pure dead weight once the app is installed. You won’t break anything deleting them.
  1. Don’t blindly trust “System Data”
    Here’s where I slightly disagree with the usual “System Data is Time Machine / caches” explanation. Sometimes it is, sometimes it’s:
  • Huge Xcode stuff (~/Library/Developer)
  • Old iOS simulators
  • Virtual machines (Parallels, VMware, UTM)
  • GarageBand / Logic Pro sound libraries

So instead of only hunting snapshots, install a disk map tool temporarily (DaisyDisk, GrandPerspective, whatever you like), run it once, take note of the real hogs, clean manually, then uninstall the tool. You get a truer picture than macOS’s vague color blob.

  1. Check for local “data copies” you forgot about
    Things that like to duplicate files:
  • iTunes / Music app:
    If you imported music, it might have copied tracks into ~/Music/Music/Media. So you could have the original files + the library copies.
  • Photos: if you manually dragged pictures into Photos and kept original folders in Pictures/Downloads, you have two copies.

Use Finder search for .mp4, .mov, .jpg, .png, etc., sort by size and location. If you see the same giant video both in “Downloads” and inside your Photos Library, you can usually delete the original from Downloads.

  1. Chrome and other browsers are secret hoarders
    Chrome especially loves caches and profiles.

Check:
~/Library/Application Support/Google/Chrome
and
~/Library/Caches/Google/Chrome

Do not delete the entire “Google” folder if you care about your profiles and passwords, but you can quit Chrome and clear the Caches subfolder. Same idea for other browsers.

  1. Check if you’re using “Downloads” as a landfill
    Storage tools kind of show this, but here’s a quick manual trick:
  • Open Downloads in Finder
  • Switch to List view
  • View > Show View Options
  • Sort by Size
    You’ll usually find old installers, Zoom recordings, random screen recordings, and multi‑GB crap you forgot about. If downloads has like 30 GB, that’s an easy win.
  1. Sanity check: are you basically outgrowing the SSD?
    If you’ve:
  • Cleaned obvious junk
  • Optimized Photos / cloud storage
  • Removed old backups and DMGs
  • Emptied Trash
  • Restarted

…and you’re still constantly under, say, 20 GB free on a 256 GB drive, the honest answer is you are just trying to live your life out of a shoebox. No amount of “tuning” fixes a 256 GB drive stuffed with 200 GB Photos, 80 GB games, and 50 GB video projects.

At that point, best realistic options:

  • Offload big, cold data (old video projects, archives) to an external SSD
  • Move game libraries to an external drive if supported
  • Seriously consider a bigger internal SSD next Mac

Bottom line:
Use the system Storage panel like @reveurdenuit said to get the overview, but lean hard on Finder’s search by size and a one‑time visual disk map to figure out exactly which folders are killing you. After that, it becomes less “mysterious System Data blob” and more “oh, Steam and six old 20 GB installers are eating my drive.”

4

Skip the flashy graphs for a second and go straight to the practical stuff that macOS doesn’t surface clearly.

  1. Use “About This Mac” only as a rough compass
    That Storage bar is approximate. I actually disagree with relying on it for decisions. Use it to see “I’m nearly full,” then move on. The “System Data” number especially is often misleading and lags behind reality.

  2. Look for hidden “local backup” behavior
    If you use:

  • Messages in iCloud
  • iCloud Drive Desktop & Documents
  • Photos with iCloud
    macOS will keep a lot of data locally even if it lives in the cloud.

Check:

  • Messages > Settings > iMessage > “Keep messages”: If set to “Forever,” chats with lots of media pile up. Switch to 1 year or 30 days if you can live with that.
  • iCloud Drive: Open iCloud Drive in Finder and watch which items have a cloud icon. Right click big folders and choose “Remove Download” to keep them in iCloud but free local space.
    This is often cleaner than deleting things outright.
  1. Audit “helper” apps that stash data in your user Library
    A lot of the bloat on nearly full Macs is not in your obvious folders at all. Examples:
  • Note taking apps that cache attachments
  • Podcast or audiobook apps that keep downloaded episodes
  • Screen recorder utilities that autosave raw captures
    Inside ~/Library/Application Support and ~/Library/Containers, look for app names you no longer use. If you know you have uninstalled the app and do not need its data, you can remove those folders. Quit the app first if it is still installed.
  1. Use a single-purpose “disk map” briefly, then delete it
    I half agree with @reveurdenuit about third party tools, but I think people overdo it and leave them running. Install one disk visualizer, run it once to identify a few huge directories, then uninstall it. That avoids long term background daemons while still revealing things like:
  • Old video project folders
  • Massive sample libraries
  • Giant archive folders you forgot about
  1. Be careful with “cleaner” style automation
    Automated cleaners can be useful, but:
  • Pro: Fast one click removal of logs, caches, old language files.
  • Pro: Helpful warnings about very large forgotten folders.
  • Con: They sometimes overreach and remove caches that actually save your time and bandwidth.
  • Con: Some run constant background agents that eat RAM and CPU on already constrained Macs.

If you use a “How To Check Storage On Mac” type guide or app approach, keep it scoped to viewing and confirming what is large, then delete manually where possible.

  1. Trash and Mail are pure low hanging fruit
    Two places people forget:
  • Mail app: Mail > Settings > Accounts > look for “Download Attachments”. Setting it to “Recent” reduces local storage use over time. Old giant attachments remain on the server.
  • Trash: Right click the Trash in Dock, turn on “Empty Trash Automatically” in Finder settings, or just make it a habit to empty it after large cleanups.
  1. Decide what actually belongs on the internal SSD
    If you work with:
  • Large video projects
  • Big sample libraries
  • Games with 50 GB installs
    those are usually better on a fast external SSD once your internal disk is regularly under pressure. At that point the issue is not so much “How to check storage on Mac” but “What should I never keep on a tiny internal drive.”
  1. When in doubt, move before you delete
    For anything irreplaceable or not easily redownloaded, move it first to:
  • External SSD
  • Cloud storage provider
    Use Finder to move whole project folders, confirm they open and work there, then remove them from the internal drive. This is safer than trusting a cleaner to decide.

@reveurdenuit already covered the built in macOS views and some smart Finder tricks, so combine that with a quick one time disk map and a reality check about what truly has to live on the internal disk. That combination solves most “almost out of space and apps crashing” scenarios without getting into risky system poking.