How to Free Up Storage on macOS Sequoia

A 512GB MacBook Air running Sequoia ran out of space last week. The user had 30GB of personal files. Where did the other 480GB go? About 90GB of System Data (Sequoia accumulates this fast), 60GB of Photos library, 30GB of stale iOS backups, 18GB of Xcode caches the user thought they’d uninstalled, and a long tail of forgotten downloads.

Sequoia is particularly good at hiding storage. Here’s how to find it.

Where Sequoia hides space (the version-specific stuff)

Most storage guides tell you to look at the same five folders. Sequoia added several new ones that older guides miss:

• ~/Library/Group Containers/group.com.apple.iphonemirroring/Caches/ — iPhone Mirroring cache, can hit 8GB
• ~/Library/Caches/com.apple.bird/ — iCloud Drive cache; Sequoia uses this more aggressively
• /Library/Apple/usr/share/rosetta/ — Rosetta 2 stage; small, but new in Sequoia’s structure
• ~/Library/Caches/com.apple.AppleIntelligenceReport/ — Apple Intelligence diagnostic data
• /private/var/folders/*/T/ — system temp; Sequoia’s tmpfs cleanup is less aggressive than Sonoma’s

These weren’t problems on Ventura. They’re routine offenders on Sequoia.

Step 1: Check the storage breakdown honestly

System Settings → General → Storage. Wait a full minute for the bars to settle — they update slowly.

Click the small arrow next to each category to see what’s in it. The categories that lie the most:

• System Data — the big offender. Sequoia includes more in this category than Ventura did, including Photos analysis, Apple Intelligence cache, and iPhone Mirroring data.
• Documents — includes downloads, desktop, anything in Documents. Often surprisingly large.
• macOS — should be 15–20GB. If it’s 40GB+, you have a stuck installer or an old recovery partition.

Click “Documents” first. Sort by size. The biggest files are usually downloads, video projects, or stuff dragged onto the Desktop years ago and forgotten.

Step 2: Empty the obvious low-value places

Quick wins, in order of likely impact:

1. Downloads folder — ~/Downloads/. Sort by date. Anything older than a month, you don’t need.
2. Trash — empty all bins (right-click each in the dock and choose Empty).
3. Desktop — anything you saved here intending to deal with later. Sort by date.
4. Movies folder — old screen recordings, video downloads, exports.
5. Old iOS backups — ~/Library/Application Support/MobileSync/Backup/. Sort by date, keep the most recent, delete the rest.

This usually recovers 20–50GB without any technical effort.

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Step 3: Clear the iPhone Mirroring cache

This is Sequoia-specific and almost no other guide covers it.

1. Quit iPhone Mirroring.app entirely (Cmd+Q from the menu bar).
2. Finder → Cmd+Shift+G.
3. Paste: ~/Library/Group Containers/group.com.apple.iphonemirroring/
4. Move the Caches folder to Trash.

macOS rebuilds what it needs the next time you mirror. On heavy users this recovers 5–8GB.

Step 4: Photos library — the silent giant

If you have iCloud Photos and “Optimize Mac Storage” off, your Mac stores every photo and video at full resolution. A 5-year-old library is often 80–150GB.

System Settings → Apple ID → iCloud → Photos. Toggle on Optimize Mac Storage. The Mac will offload full-resolution originals to iCloud and keep smaller versions locally. You can still view everything; macOS streams the originals when you need them.

If you don’t use iCloud Photos, the Photos library is on your Mac in full and there’s no shortcut. Either move it to an external drive (hold Option while opening Photos to choose a different library location) or delete photos you don’t need.

Step 5: Mail attachments

Mail downloads attachments aggressively, even when you’re using IMAP and they’re already on the server.

System Settings → Mail (or Mail.app → Settings → Accounts → Account Information → Download Attachments). Set to “Recent” or “None” instead of “All”.

Then, to clear what’s already cached:

~/Library/Mail/V10/MailData/

Inside, the per-account folders contain Attachments/. You can delete these contents safely; Mail re-downloads on demand. Quit Mail first.

A heavy email user often has 10–20GB in Mail attachments alone.

Step 6: App caches

Sequoia’s biggest cache offenders:

• Xcode — ~/Library/Developer/Xcode/DerivedData/ and ~/Library/Developer/CoreSimulator/Caches/ (10–50GB)
• Chrome / Arc / Brave — ~/Library/Caches/Google/Chrome/Default/Cache/, ~/Library/Caches/com.thebrowser.Browser/
• Slack — ~/Library/Application Support/Slack/Cache/ and Service Worker/
• Spotify — ~/Library/Caches/com.spotify.client/Data/
• Photos — ~/Pictures/Photos Library.photoslibrary/resources/streaming-thumbnails/

Quit the app first, then drag its cache to Trash. macOS will rebuild what’s actually needed.

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Step 7: Old macOS installers and update files

Sometimes Sequoia leaves a “Install macOS Sequoia.app” in /Applications/ after the update. It’s 13GB and you don’t need it. Drag to Trash.

Also check /Library/Updates/ for partially-downloaded update files. Empty if present.

For Time Machine local snapshots — Sequoia keeps these even when you’re not on a Time Machine drive. Open Terminal:

tmutil listlocalsnapshots /

If you see a list, delete the oldest:

tmutil deletelocalsnapshots <date>

These can take 20–40GB on their own.

Step 8: Apple Intelligence cache

If you’ve enabled Apple Intelligence on Sequoia, the model files and analysis cache live in:

• ~/Library/Caches/com.apple.AppleIntelligenceReport/
• ~/Library/Apple Intelligence/ (if you’ve used Image Playground or Genmoji extensively)
• /System/Library/AssetsV2/com_apple_MobileAsset_* for the foundation models

You shouldn’t manually delete the system-level model files (macOS will redownload them, wasting bandwidth and time). But the user-level cache is fair game if you’re tight on space.

Step 9: Languages and keyboard layouts you don’t use

Most apps ship localized resources for 30+ languages. You speak one or two. Tools like Monolingual used to handle this, but System Integrity Protection now restricts what they can touch. If you’re really tight on space, the gain is 1–3GB across all your apps — not huge.

Skip this unless you’re under 5GB free and desperate.

Step 10: Uninstall apps you don’t use, completely

Dragging an app to Trash in Sequoia leaves behind:

• ~/Library/Application Support/<AppName>/
• ~/Library/Caches/<AppName>/
• ~/Library/Preferences/<AppName>.plist
• ~/Library/Logs/<AppName>/
• Sometimes login items and launch agents

A complete uninstall hunts these down. Manually it’s tedious. Sweep’s app uninstaller does it in one click and shows you exactly what’s getting deleted before it commits.

Step 11: Move what you can to external storage

If after all of the above you’re still tight, the realistic next step is offloading large libraries:

• Photos library — easy to relocate
• Music library — same
• Video projects — Final Cut and iMovie support external libraries natively
• Old document archives — anything older than a year you rarely access

A $60 1TB external SSD via USB-C is a one-time purchase that solves the “running out of space” problem permanently for most users.

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Maintenance going forward

Sequoia rewards monthly maintenance: clear Downloads, empty Trash, flush iPhone Mirroring cache, glance at Storage. Twenty minutes a month keeps the System Data bar from creeping up to 80GB.

The two factors that matter most: Downloads folder size, and whether you’ve ever cleaned out old iOS backups. Address those two and you’ve solved 70% of the storage problems Sequoia users hit.