How to Free Up Space on macOS: 10 Places to Look First

“Your disk is almost full” is one of the more unhelpful warnings macOS shows you, because it doesn’t tell you where to look. Most people respond by emptying Downloads and calling it done, which rarely frees more than a gigabyte. The real space is almost always somewhere macOS doesn’t put in front of you by default.

Here are the ten places that consistently hold the most reclaimable space, roughly ordered by how much they tend to give back.

1. Application and system caches

~/Library/Caches accumulates temporary data from every app you use (browsers, IDEs, chat apps, Adobe products) and none of it needs to be there permanently. It’s regenerated automatically as needed. On an active Mac this is routinely 5-15 GB. See how to delete cache on Mac for the safe way to clear it without breaking anything.

2. Xcode DerivedData, archives, and simulators

If Xcode has ever been installed, check ~/Library/Developer/Xcode. DerivedData (build intermediates and the code index) is always safe to delete and rebuilds on the next build. Old .xcarchive files from App Store submissions and unused iOS Simulator devices pile up for years unless someone actively prunes them. This category alone commonly reaches 15-20+ GB on a Mac used for iOS development. See OverClean’s Xcode & Simulator Artifacts view for a breakdown by type.

3. Old iOS backups

Finder-based iPhone and iPad backups live in ~/Library/Application Support/MobileSync/Backup/ and are never cleaned up automatically, even after you’ve upgraded devices multiple times. Check this folder directly if you’ve ever backed up a device to your Mac.

4. Local Time Machine snapshots

Even without an external backup drive connected, macOS keeps hourly local snapshots on your internal disk. They’re meant to thin themselves out under storage pressure, but on a Mac that’s chronically near capacity, that automatic housekeeping can lag behind.

5. node_modules, virtual envs, and Docker data

Every JavaScript project you’ve ever cloned or scaffolded left a node_modules folder, often hundreds of megabytes each. Python projects leave .venv or venv directories the same way. Docker Desktop’s images, containers, and volumes live in a single large VM disk file that only grows. None of these show up when you sort your Documents folder by size. See Development Tools for a scan that finds them across your whole disk.

6. Leftover files from uninstalled apps

Dragging an app to the Trash doesn’t remove its preferences, caches, or Application Support data. That stuff stays behind indefinitely with no app left to claim it. Years of installing and removing apps adds up. Full process in how to uninstall apps on Mac completely.

7. Mail and Messages attachments

Mail downloads and caches every attachment locally, and Messages does the same for photos and videos sent over iMessage. If you’ve been on the same Mac for a few years with iCloud Mail or a large inbox, this can quietly hold several gigabytes in ~/Library/Mail and ~/Library/Messages/Attachments.

8. Duplicate and forgotten large files

Video exports, disk images (.dmg), old VM files, and duplicate downloads tend to collect in Downloads and Desktop because deleting them requires actively remembering they exist. A size-sorted view across your whole disk (not just Documents) makes these obvious in a way Finder’s default folder-by-folder browsing doesn’t.

9. Unused applications

Apps you installed once, tried, and forgot about still take up their full install size indefinitely. The Applications manager sorts every installed app by real size, including embedded frameworks that Finder’s Get Info panel doesn’t count, so the worst offenders are easy to spot.

10. System Data / “Other” storage

Apple’s own Storage view lumps a huge range of things into “System Data,” a category with almost no actionable detail. It’s usually a mix of several items on this list plus system logs and caches. We cover how to actually break this bucket down in what is taking up space on my Mac.

How much space should you actually expect back?

It depends heavily on how you use the Mac, but rough ranges from the categories above give you a sense of what’s realistic. Caches alone: 5-15 GB on an active daily-use Mac. Development clutter (node_modules, Docker, Xcode): anywhere from a few GB to 30+ GB if you’ve done years of iOS or web development without ever pruning it. Old iOS backups and Time Machine snapshots: 10-30 GB combined if you’ve upgraded devices a couple of times. Leftover app files: typically 2-8 GB after several years of installing and removing software.

Put together, it’s common for a Mac that “feels full” to have 30-60 GB of reclaimable space once every category above is checked. That’s often enough to go from a red storage bar back to comfortable headroom without deleting a single photo or document.

A quick sanity check before you clean anything

Before deleting, it’s worth distinguishing storage-full symptoms from a different problem entirely: a Mac that has plenty of free space but still runs slowly. If your storage bar shows healthy free space and performance is still the complaint, the cause is more likely background processes, memory pressure, or login items than disk space. See Mac running slow, how to fix it for that diagnosis instead.

The fastest way to check all ten at once

Going through this list manually with Finder and Terminal works, but it’s slow and easy to get wrong, especially for hidden folders under ~/Library that Finder doesn’t show unless you know the keyboard shortcut to reveal them. A dedicated scan checks all of these categories in one pass and shows real sizes instead of estimates.

Download OverClean for a free scan of your Dashboard and category breakdown, no account needed. For the deeper Applications, Leftovers, and Development Tools views that cover items 2, 5, 6, and 9 above, see pricing.