What's Eating Your Mac's Storage? Finding and Removing Large Files

You open System Settings > General > Storage, and the bar chart shows a massive "System Data" or "Other" category eating 50+ GB. What is this, and what can you do about it?

What "System Data" actually contains

Apple's storage categories are intentionally vague. "System Data" (previously called "Other" in older macOS versions) is a catch-all for everything that doesn't fit into Documents, Apps, Photos, or Music. This includes:

• Application caches — Cached data from apps like Slack, Spotify, Chrome
• System logs and reports — Diagnostic data, crash reports
• Time Machine local snapshots — Backup snapshots stored on your local drive
• Xcode and developer data — Build artifacts, simulator images, device support files
• Virtual machine images — Parallels, VMware, or Docker images
• Old iOS backups — Device backups from iTunes/Finder
• Mail attachments — Downloaded email attachments

Common large file types

When hunting for space, these are the usual suspects:

Videos (.mp4, .mov, .avi, .mkv) Screen recordings, downloaded videos, and camera imports can be 1-10 GB each. They're easy to forget about, especially in nested folders.

Disk images (.dmg, .iso) macOS installer images and downloaded disk images. The macOS installer alone is 12+ GB. Old installer .dmg files from apps accumulate in your Downloads folder.

Virtual machine images (.vmdk, .vdi, .qcow2) If you use Parallels, VMware, or Docker, VM images can be 20-100+ GB each. Even unused VMs consume disk space.

Archives (.zip, .rar, .7z) Downloaded archives that you've already extracted but never deleted.

Documents (.pdf, .docx, .pptx) Individual documents are usually small, but large PDFs (scanned documents, design files) can be hundreds of MB.

The risk of blind deletion

The temptation is to sort by size and delete the biggest files. But this approach has risks:

• That 5 GB file might be a database your app needs
• The large folder might contain a project you're still working on
• Some large files are system files that shouldn't be touched

Understanding what a file is before deleting it is crucial.

Using macOS built-in tools

macOS has a built-in storage management tool:

1. Open System Settings > General > Storage
2. Click the (i) button next to any category
3. Review files and delete what you don't need

This works for basic cases but doesn't show files in hidden folders, doesn't categorize by file type, and doesn't help with developer-specific data.

A more thorough approach

CleanMyMacOS includes a Large File Scanner that finds files above a configurable threshold (default 100 MB) and organizes them into 7 categories: Videos, Archives, Installers, Disk Images, Virtual Machines, Documents, and Other. You can scan any folder and review files sorted by size (largest first) before deciding what to remove.

The Storage Map feature provides an interactive visualization of your disk usage with radial and tree views, letting you drill down into exactly what's consuming space.

Everything is presented with context — file type, size, location, and modification date — so you can make informed decisions rather than guessing.

CleanMyMacOS can help with this — download it free from the Mac App Store.