How do I compress mp3 audio file to small size?

Fra:ac is a free, versatile, and user-friendly audio converter that works well on Windows for compressing MP3 audio files in batch. Here's a step-by-step guide to help you get started with compressing MP3 files using Fra:ac:

1. Run the installer and follow the prompts to install.
2. Open the program after installation.
3. Click "Add Files" or "Add Folder" to select the MP3 files or folders containing your high-quality MP3s. All selected files will appear in the list.
4. Click "Encoder" or "Configuration" (depending on the version).
5. Under "Encoder", select MP3 (LAME)".
6. Click "Configure" next to the encoder to set the parameters:

   * Bitrate: Choose a lower bitrate (e.g., 128 kbps or 96 kbps).
   * Sample rate: Keep default or lower if desired.
   * Channels: Stereo or mono (mono reduces size further but may affect audio quality).
   * Quality: Select a balance between quality and size.

7. Specify where you want the compressed files to save under "Output folder".
8. Once everything is set, click "Start".
9. Fra:ac will process all files, converting them to lower bitrate MP3s.
10. Check the output folder for your compressed MP3 audio files.
11. Play them to verify acceptable audio quality.