Switch -M<n> - set compression method

Choosing <n> from 0 to 5 you may select an appropriate compression method

-m0 Store Add files to archive without compression
-m1 Fastest Fastest method (least compressive)
-m2 Fast Fast compression method
-m3 Normal Normal (default) compression method
-m4 Good Good compression method (more compressive)
-m5 Best Best compression method (most compressive but also most slow)

If this switch is not specified, WinRAR uses "-m3" method (Normal compression).

By default, WinRAR uses only the general compression algorithm in -m1 and -m2 methods, advanced algorithms like audio and true color processing are enabled only in -m3..-m5 modes, the advanced text compression is activated only in -m4..-m5. This default can be overridden using -mc switch.

The compression method also can be selected through the "Compression method" list in the Archive name and parameters dialog.