MacBook Air 2020 storage full: Free space & backup help

Ok, based on what you provided, here's what I suggest your next steps should include:

Step 1: Back up your Mac (high priority)

Since you’ve never backed up before, I strongly recommend using an external drive that’s at least 1 TB to give you room to grow. Reliable options include drives from brands like Samsung, SanDisk, or Western Digital. Once connected, go to System Settings → General → Time Machine, select the external drive, and let Time Machine complete a full backup. The first backup may take several hours, so it’s best to leave the Mac plugged in and undisturbed.

Step 2: Identify what’s actually using space

Go to System Settings → General → Storage and allow it a minute to calculate. “System Data” often looks alarming, but it usually includes caches, logs, local snapshots, and iOS backups. Click each category, especially Applications, Documents, and Mail, and sort by size to find the biggest offenders.

Step 3: Free space safely

• Enable Optimize Storage and Empty Trash Automatically from the Storage recommendations
• Remove applications you no longer use (many apps can be reinstalled later)
• Check for large files like old installers, videos, or downloads
• Restart the Mac after cleanup to help macOS clear temporary system data

Step 4: Get enough space for updates

macOS updates typically need 20–30 GB free. After the above steps, you should have enough space to update safely.

Shamrock234 wrote:

Also, which external hard drive should I get? When looking at the San disk the option of SSD vs HDD? Probably overkill to get SSD for my purposes but would that be better for use in the long run, paying a little extra for quality and better long term use? I didn't realize the big difference in cost. I don't need a rugged one either.

HDDs are still considerably cheaper than SSDs. Over time, that may change, but even today (in 2026), you can find HDDs with large storage capacities at reasonable prices.

The following are my suggestions for you to consider on external HDDs in the 1 TB – 2 TB storage capacities for Time Machine backups and general Mac file storage — all proven reliable, broadly compatible with macOS (and easy to format APFS for backup use), and built to last for everyday use. Not listed in any particular order:

• WD My Passport for Mac Portable Hard Drive
• Toshiba Canvio Advance Plus 2TB Portable External Hard Drive
• WD My Passport Ultra Hard Drive

This is what I am referring to ... although I am currently running macOS Tahoe, not Sequoia. It's located at: System Settings > General > Storage. UPDATE: I just checked with Sequoia and it's in the same location.

"MacBook Air 2020 storage full: Free space & backup help: I have a macbook air 2020 and storage is full so I can't do any updates. I was debating on getting a new MacBook air 13" but since a new one is likely coming out in spring 2026 I should probably wait. I have never backed up my computer, what external hard drive should I use to back it up now? Also, what is best way to free up some storage? Most of the space seems to be system data, mac OS and applications. I have 245 GB storage. Thanks!"

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Clear the Caches:

How much of the internal space is System Data? If lots, you can clear it, and then you'll have plenty of space. Go to: Applications > Utilities > Disk Utility

Use my User Tip for this: How to Use Finder to Clear “System Data" on a Mac - User Tip