Investigate Compressed Files in WizTree

Short answer: Compression can make content size a poor predictor of its occupied space.

By DiskAnalyzer editorial resource · Published 2026-10-05 · Documentation reviewed 2026-10-05

When this guide is useful

A text-heavy archive and a folder of already compressed videos may respond very differently. Measure the specific workload and consider access performance and backup behavior before changing compression settings.

Recommended workflow

Compare logical and allocated values.
Check file attributes in Windows.
Identify which program manages the compressed files.
Measure available space after any approved change.

Limits and precautions

Do not promise a fixed storage saving from compression.

Keep a useful record

Record the drive or folder, scan time, application version and the measurement you used. Keep observations separate from proposed changes. If a result leads to a cleanup, record the file owner, backup status and actual free-space change. This makes the result easier to review and helps explain differences in a later scan.

Quick review checklist

Question	What to record
What did you inspect?	The exact volume or folder, not just the PC name.
What action is justified?	Measure available space after any approved change.
What could go wrong?	Do not promise a fixed storage saving from compression.

Next steps

If the result is unclear, preserve the current report and narrow the investigation to one folder or application. Make one approved change at a time, then repeat the relevant measurement. Avoid presenting a predicted saving as a measured outcome.

Sources and verification

Prepared from public documentation and practical storage-audit reasoning. No hands-on Windows test or independent binary inspection was performed for this publication. Menu names and package requirements can change; check the developer documentation for your installed version.