GigapolisHow to free up disk space on a Mac
To free up disk space on a Mac, first find out what's using it, then clear the biggest things you don't need: caches, local Time Machine snapshots, old downloads, large files you've forgotten, unused apps and duplicate photos. This guide walks through each one using only what's built into macOS, and shows the faster route with Gigapolis at the end of each step.
In this guide
Before you delete anything: make sure you have a recent backup. Move things to the Trash rather than deleting them outright, so you can put them back if something goes wrong.
1. See what's using your storage
Open System Settings → General → Storage. The bar at the top splits your disk into Applications, Documents, Photos, System Data and so on. Underneath, macOS offers a few recommendations, and the ⓘ button next to each category lists its files.
The built-in view is a good start, but it can't show you inside System Data, and it doesn't show which folders are biggest. A disk space analyzer fills that gap. Gigapolis scans your whole disk and draws it as a 3D city, with one building per category: the tallest building is what's using the most space, and clicking it lists the files inside, biggest first.
2. Empty the Trash
Files you've deleted still take up space until the Trash is emptied. Right-click the Trash in the Dock and choose Empty Trash. To do this automatically, open Finder, choose Finder → Settings → Advanced and turn on Remove items from the Trash after 30 days.
Apps like Photos and Mail have their own trash too: check Recently Deleted in Photos and the Deleted folder in Mail.
3. Clear out old downloads
The Downloads folder quietly fills up with installers (.dmg and .pkg files), zips and one-off documents. In Finder, open Downloads, switch to list view (⌘2) and sort by Size or Date Added. Installers for apps you've already installed are safe to remove.
Gigapolis's free Street Sweep lists downloads you haven't touched in over 60 days, alongside caches and the Trash, so you can clear them in one go.
4. Find and remove large files
A handful of big files, such as old video projects, disk images or virtual machines, often take more space than thousands of small ones. Our guide on how to find large files on a Mac covers three ways to track them down, including Finder search by file size.
5. Clear caches
Caches are files apps keep to load things faster. They're safe to clear because apps rebuild what they need, but some grow to several gigabytes. See how to clear cache on a Mac for the user cache folder and each browser.
6. Shrink System Data
If the Storage bar shows a huge grey System Data section, it's usually local Time Machine snapshots, caches and logs. Our guide What is System Data on a Mac? explains what's in it and what's safe to remove.
7. Uninstall apps you don't use
Dragging an app to the Trash removes the app, but often leaves its support files behind in ~/Library/Application Support, ~/Library/Caches and ~/Library/Containers. In System Settings → General → Storage → Applications you can sort apps by size and see when you last used them.
Gigapolis's free App Uninstaller removes an app together with the leftovers it can match to it, and Pro's Deep Clean finds leftovers from apps you removed in the past.
8. Remove duplicate photos
The Photos app has a built-in Duplicates album (macOS Ventura and later) in the sidebar under Utilities, where you can merge exact and near-exact copies. Gigapolis's Photo Studio also finds look-alike shots, such as bursts of the same scene, and picks the sharpest copy for you to keep.
9. Let iCloud store older files
If you pay for iCloud storage, Store in iCloud (in the Storage settings) keeps recent files on your Mac and older ones in the cloud, downloading them when you open them. It doesn't delete anything, but it does mean those files need the internet to open.
Do all of this from one window
Gigapolis shows your storage as a 3D city, so the space hogs stand out at a glance. Street Sweep, Maintenance and the App Uninstaller are free (up to 20 GB of clean-up a month). Everything goes to the Trash first, and system folders are never touched.
Questions
How much free space should a Mac have?
Aim to keep at least 10–15% of your disk free, or around 20 GB on smaller drives. macOS needs room for updates, swap files and caches, and gets slow when the disk is nearly full.
Is it safe to delete System Data on a Mac?
Not all of it. Caches, old logs and local Time Machine snapshots are safe to remove. Core macOS files are not, and you can't delete them anyway without turning off system protection.