Running Out of Disk Space? How to Find What’s Filling Your Drive

“Your disk is almost full.” It’s a warning almost every computer user sees eventually. And it matters: a nearly full drive slows your computer, can stop updates from installing, and leaves no room for new files.

How much free space do you need?

A good rule of thumb is to keep at least 10–15% of your drive free, or around 20 GB minimum on smaller drives. Major system updates can need even more temporarily.

Step 1: See what’s using the space

Don’t delete things blindly. Find the big items first.

• Windows: Settings → System → Storage. You’ll see a breakdown by category (apps, temporary files, documents, pictures and more). Click Show more categories for detail.
• Mac: System Settings → General → Storage. Click the ⓘ next to each category to review files.
• For more detail: Free tools like WinDirStat or WizTree (Windows) and GrandPerspective or DaisyDisk (Mac) show a visual map of exactly which folders are biggest.

Step 2: Quick, safe wins

Empty the Recycle Bin or Trash

Deleted files still take up space until you empty it.

Clean up temporary files

• Windows: Settings → System → Storage → Temporary files. Review the list and remove what you don’t need. Be careful with the Downloads option, which deletes everything in your Downloads folder.
• Windows: Settings → System → Storage → Cleanup recommendations suggests large files and unused apps.
• Mac: In Storage settings, review the Recommendations section.

Turn on automatic cleanup

• Windows: Turn on Storage Sense to automatically clear temporary files and old Recycle Bin contents.
• Mac: Turn on Empty Trash Automatically in Storage settings.

Step 3: Find the big stuff

The usual suspects:

• Downloads folder: installers, old videos and files you’ve forgotten about.
• Videos: phone videos, screen recordings and downloaded movies are huge.
• Old phone backups: iPhone backups on a computer can take many gigabytes.
• Games: modern games can take 100 GB or more each.
• Duplicate photos: especially if you’ve imported the same phone photos multiple times.

Step 4: Uninstall apps you don’t use

• Windows: Settings → Apps → Installed apps → sort by Size.
• Mac: Drag unused apps from the Applications folder to the Trash, or use Storage settings → Applications.

Step 5: Use cloud storage smartly

OneDrive, iCloud Drive and Google Drive can keep files online only until you need them:

• OneDrive: Right-click a folder → Free up space.
• iCloud: Turn on Optimize Mac Storage in iCloud Drive settings.

Your files still appear in folders but only download when opened.

Step 6: Move files to an external drive

Large archives like old photos, finished projects and video are good candidates for an external drive. Just remember: if a file exists in only one place, it isn’t backed up.

What NOT to delete

• Files in C:\Windows, Program Files or macOS System folders.
• Anything labeled as a driver, recovery partition or system file.
• hiberfil.sys and pagefile.sys files directly (Windows manages these).

When in doubt, leave it alone.

Step 7: Consider a bigger drive

If you’re constantly fighting for space, upgrading to a larger SSD (where your computer allows) or adding a large external drive may be the long-term fix.

The bottom line

Look before you delete. Use the built-in storage tools to find the big items, clean up temporary files, uninstall what you don’t use, and let cloud storage handle files you rarely open.