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  • System

Logs and crash reports: usually small, occasionally enormous

macOS keeps logs in four places and rotates most of them. When one grows to gigabytes it means something specific, and that is the useful signal.

5 min read

Log files are the classic cleanup advice and usually the wrong target. macOS rotates and compresses its own logs, and on a healthy Mac the whole lot comes to a few hundred megabytes. The reason to look is not the space; it is that a genuinely large log folder tells you something is repeatedly failing.

The four places

du -sh ~/Library/Logs /Library/Logs /var/log \
  ~/Library/Application\ Support/CrashReporter 2>/dev/null | sort -h
LocationWhat it holds
~/Library/LogsYour applications' logs and crash reports
/Library/LogsSystem wide application logs
/var/logUnix system logs, rotated automatically
/Library/Logs/DiagnosticReportsCrash and panic reports sent to Apple

Reading a large one instead of deleting it

If one folder is disproportionate, sort by name and look at what repeats:

ls -S ~/Library/Logs | head -10
ls -S /Library/Logs/DiagnosticReports 2>/dev/null | head -10

Twenty crash reports for the same application in a week is a broken app, and removing the reports changes nothing about that. An application writing a gigabyte log is usually stuck in a retry loop, and quitting or reinstalling it is the actual fix.

What is safe to remove

  • Crash and diagnostic reports. Safe. They are copies of reports already sent, kept for your reference.
  • Application logs in ~/Library/Logs. Safe, and rewritten as apps run.
  • /var/log archives. Managed by the system. Leave them; they rotate on their own.
  • The unified log store. Not a file you delete. macOS caps it and manages it itself.

The unified log, which people mistake for a folder

Since macOS moved to the unified logging system, most of what used to be text files is a binary store the system manages with its own size limit. There is nothing useful to clean there, and advice telling you to delete it is out of date by about a decade.

Where the space actually is

On almost every Mac, logs are a rounding error next to caches, snapshots and media. If you arrived here from a full disk, what System Data is made of and the order to free 100 GB will get you further than any log folder.

Common questions

Is it safe to delete log files on a Mac?

Application logs and crash reports under ~/Library/Logs and /Library/Logs/DiagnosticReports are safe to remove. Leave /var/log alone, since the system rotates it, and there is nothing to delete in the unified log store that macOS manages itself.

How much space do logs use on a Mac?

Usually a few hundred megabytes at most. On a working Mac measured in September 2026, ~/Library/Logs was 13 MB. A log folder in the gigabytes means an application is failing repeatedly rather than that logs need cleaning.

What are diagnostic reports on a Mac?

Crash, hang and kernel panic reports, kept in /Library/Logs/DiagnosticReports. They are local copies of the reports macOS offers to send to Apple, and they can be deleted freely once you have no use for them.

Why does one app have dozens of crash reports?

Because it is crashing repeatedly. Each crash writes a new report. Deleting the reports frees a trivial amount of space and does not address the app, which usually needs updating, reinstalling or removing.

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