Help · Mac storage

Moving Xcode simulators to an external drive.

By Grant and Brad, who make Pangalin's apps · Updated 14 October 2026

Each simulator runtime (the copy of iOS, watchOS, tvOS or visionOS the Simulator boots) takes several gigabytes, and every simulated device keeps its own apps and data. Short answer: Apple has no supported way to keep them on an external drive. What you can do is remove the ones you don't use, and keep spare runtime downloads on the external drive instead.

Where the space goes

• Simulator runtimes. macOS keeps these in a protected system area that Xcode's simctl tool manages. Usually the biggest part.
• Simulated devices (~/Library/Developer/CoreSimulator/Devices): one folder per device, holding the apps you installed on it and their data.
• Simulator caches (~/Library/Developer/CoreSimulator/Caches): rebuilt by the Simulator.

See what you have

1. In Xcode choose Xcode › Settings and click Components. Apple says it lists what's installed along with the amount of storage you can recover by removing it.
2. Or in Terminal, list the installed runtimes and their sizes:
   xcrun simctl runtime list
3. List your simulated devices:
   xcrun simctl list devices
4. See how much the devices take:
   du -sh ~/Library/Developer/CoreSimulator/Devices

Remove what you don't use

Everything here deletes permanently. Removing a device deletes the apps and data on it. Removing a runtime means downloading it again (several gigabytes) before you can use it. Quit Xcode and the Simulator first.

• A runtime: in Xcode › Settings › Components, click the information button next to it, then Delete. You can get it back later from the same place.
• Devices Xcode can no longer use: this deletes the simulated devices that the current Xcode doesn't support:
  xcrun simctl delete unavailable
• Old runtimes: simctl can remove runtimes that have a newer version installed. Add --dry-run first to see what it would delete:
  xcrun simctl runtime delete --outdated --dry-run
  then run it again without --dry-run. To remove runtimes you haven't used in, say, 90 days, use --notUsedSinceDays 90 instead of --outdated.
• One device: remove it in Xcode's Window › Devices and Simulators.

Don't delete runtime files in Finder. They're owned by the system and tracked by the Simulator's own records, so removing them by hand can leave Xcode confused. Use Xcode or simctl.

Can they live on an external drive?

Not in a way Apple supports. Xcode has no setting to keep simulator runtimes or simulated devices on another drive, and Apple doesn't document one. Runtimes sit in a protected system area, so don't try to move or link them. You'll find guides that move the Devices folder and leave a symbolic link behind. Apple doesn't support that, and whenever the drive isn't connected Xcode and the Simulator can't reach your simulated devices. We don't recommend it.

The supported alternative: keep runtime downloads on the drive

Apple's xcodebuild can save a runtime as a file instead of installing it. Keep these files on your external drive, remove runtimes you rarely use from your Mac, and install one again from the drive when you need it, without downloading it again.

1. Download a runtime to the drive (replace MyDrive with your drive's name):
   xcodebuild -downloadPlatform iOS -exportPath /Volumes/MyDrive/Runtimes
   Add -buildVersion and a version number, such as -buildVersion 18.0, for a particular release.
2. When you need it, install it from the drive (use the file's real name):
   xcodebuild -importPlatform "/Volumes/MyDrive/Runtimes/runtime file.dmg"
   Apple notes you may need to run xcodebuild -runFirstLaunch first.

An installed runtime always lives on your Mac's own drive. The file on the external drive is a spare copy, so it saves you the download, not the space while the runtime is installed.

Build data can move

Xcode's build data (DerivedData) is different: Xcode lets you choose where it goes, in Xcode › Settings › Locations. To clear it instead, see how to clear Xcode's cache.