Display UNRAR Compression Method as Numeric Code

This guide explains how to display RAR compression methods as numeric codes using the command-line utility unrar. By utilizing technical and verbose listing modes, users can inspect archive metadata and identify the exact compression level applied to each archived file. Below, you will find the specific commands and switches required, practical terminal examples, and a breakdown of what each numeric compression value represents.

The Switch to Display Numeric Compression Methods

To view the compression method as a numeric code in unrar, use the technical listing command lt (or vt for verbose technical output).

In unrar, listing modes function as primary commands or modifiers rather than traditional hyphenated switches:

unrar lt archive.rar

Alternatively, you can run the standard verbose listing command v:

unrar v archive.rar

Output Differences

  • unrar lt <archive.rar>: Displays a multi-line, detailed technical block for every file in the archive. Within this block, the Compression field explicitly outputs the compression parameter in numeric format (for example, -m3 -md=32m).
  • unrar v <archive.rar>: Displays a compact tabular layout with a Meth (Method) column. This column lists the compression mode as a short alphanumeric string such as m0, m3b, or m5.

Understanding the Numeric Compression Codes

RAR archives use a numeric scale ranging from 0 to 5 to indicate the algorithm's compression intensity:

  • 0 (-m0) — Store: No compression applied; files are packaged directly into the archive.
  • 1 (-m1) — Fastest: Minimal compression utilizing the lowest CPU overhead.
  • 2 (-m2) — Fast: Light compression prioritizing extraction and archiving speed.
  • 3 (-m3) — Normal: Standard balanced compression mode (default in most RAR tools).
  • 4 (-m4) — Good: Higher compression ratio requiring additional system memory and processing time.
  • 5 (-m5) — Best: Maximum compression ratio with the highest resource usage.

In tabular outputs (unrar v), trailing letters next to the number (such as m3b) represent internal format variations, dictionary types, or legacy archive compatibility flags associated with that method.