Is it safe to delete files in the Downloads folder?

Usually, yes. Downloads holds copies of things you fetched from the web or email, and most can be downloaded again. Check for anything you saved only there, like signed documents or receipts, before you empty it.

What is System Data on a Mac, and can I delete it?

System Data is caches, logs, local Time Machine snapshots, virtual memory and app support files. macOS trims most of it on its own when space gets low. Deleting files inside it by hand is risky; restarting the Mac and emptying the Trash is the safe first step.

How much free space should a Mac have?

Keep at least 10–15% of the disk free, and never less than about 20 GB. macOS needs room for updates, virtual memory and snapshots, and a nearly full disk makes the whole Mac slower.

Does Peekaboo delete files permanently?

No. Peekaboo only ever moves files to the Trash, and every cleanup can be put back in one click. Files that live only in iCloud are skipped, so nothing gets downloaded just to be checked.

Mac file guides

How to free up space on a Mac

By Vishva Variya · Updated October 31, 2026 · 6 min read

Short answer

Open System Settings › General › Storage to see which categories are largest, then clear the usual suspects: old files in Downloads, installers (.dmg, .pkg, .zip), large videos, duplicate files and apps you no longer use. Move them to the Trash, check nothing is missing, then empty the Trash to actually get the space back.

Where does the space on a Mac go?

On most Macs a handful of things account for most of the disk: video files, photo libraries, the Downloads folder, disk images and archives you opened once, apps you tried and forgot, and copies of the same file saved twice. “System Data” covers caches, logs, Time Machine local snapshots and app support files; it is real, but it is usually not where the easy wins are.

How do I check storage with macOS’s own tools?

1Open the Apple menu › System Settings › General › Storage.
2Wait for the bar at the top to finish calculating. Each colour is a category.
3Look at Recommendations: Store in iCloud, Optimize Storage, Empty Trash Automatically.
4Click the ⓘ button next to Documents to see Large Files, Downloads and Unsupported Apps, sorted by size.
5Select anything you don’t need and click Delete. This deletes immediately, so be sure.

Storage settings are good for a first look. They don’t show duplicates, they can’t tell you where a download came from, and their Delete button skips the Trash.

Which files are safe to delete?

Installers you have already run: .dmg, .pkg and .xip files, usually in Downloads.
Archives you have already unzipped, if the unzipped folder is still there.
Screen recordings and exported videos you have uploaded or shared.
Exact duplicates: two files with identical contents, where you keep one.
Apps you haven’t opened in months. Drag them from Applications to the Trash.

Leave ~/Library, system folders and anything you don’t recognise alone. Deleting an app’s support files by hand can break it, and macOS manages its own caches.

How do I find the biggest files from Terminal?

If you’re comfortable in Terminal, this lists every file over 1 GB in your home folder, largest first:

find ~ -type f -size +1G -exec du -h {} + 2>/dev/null | sort -hr

It only lists. Nothing is moved or deleted.

Why didn’t the free space go up?

The Trash still holds the files. Empty it (Finder › Empty Trash).
Photos and Mail keep their own deleted items: Photos › Recently Deleted, and Mail’s Trash mailbox.
Time Machine local snapshots hold deleted files for a while. macOS frees them on its own when space runs low.
Files stored in iCloud Drive with Optimize Mac Storage on may already be off the disk, so deleting them frees nothing locally.

Freeing space with Peekaboo

Peekaboo does the looking for you and keeps every step reversible. Space Map draws your disk as a map you can click into, and Clean Up gathers forgotten downloads, old installers, stale screenshots, big old videos and unused apps, each with the space it’s worth. Everything goes to the Trash, never straight to deletion, and each cleanup is a session you can put back in one click.

1Open Space Map to see which categories and folders are largest.⇧⌘M
2Open Clean Up and review each group before anything moves.⇧⌘K
3Run Duplicates to find identical files and look-alike photos.⇧⌘D
4Changed your mind? Undo the whole cleanup from the Undo timeline.⌘Z

Questions

Is it safe to delete files in the Downloads folder?: Usually, yes. Downloads holds copies of things you fetched from the web or email, and most can be downloaded again. Check for anything you saved only there, like signed documents or receipts, before you empty it.
What is System Data on a Mac, and can I delete it?: System Data is caches, logs, local Time Machine snapshots, virtual memory and app support files. macOS trims most of it on its own when space gets low. Deleting files inside it by hand is risky; restarting the Mac and emptying the Trash is the safe first step.
How much free space should a Mac have?: Keep at least 10–15% of the disk free, and never less than about 20 GB. macOS needs room for updates, virtual memory and snapshots, and a nearly full disk makes the whole Mac slower.
Does Peekaboo delete files permanently?: No. Peekaboo only ever moves files to the Trash, and every cleanup can be put back in one click. Files that live only in iCloud are skipped, so nothing gets downloaded just to be checked.