Cut M4B Audiobook

How to Cut M4B Audiobook

1. Upload Your M4B File — Click "Choose Files" or drag and drop your M4B audiobook file. Only .m4b files are accepted.
2. Set Cut Points — Under Trim, select "Trim" and enter a Start Time and Duration in seconds or HH:MM:SS.sss format to extract the segment you want to keep.
3. Set Audio Quality — Under File Compression, choose from: Quality Preset (Highest through Lowest), File Size Percentage (1-100% slider), Specific File Size (MB/KB), Custom Bitrate (enter any value in kbps), Constant Bitrate (32-384 kbps presets), or Variable Bitrate.
4. Adjust Audio Settings (Optional) — Under Audio Codec, the default is AAC. Set Audio Channel to Original, Mono, or Stereo. Change Audio Sample Rate from 8000 Hz through 48000 Hz.
5. Cut & Download — Click "Convert" and download your cut M4B file.

Why Cut M4B Audiobook Files?

M4B (MPEG-4 Audio Book) is Apple's audiobook format with bookmarking and chapter support. Cutting M4B files is useful for extracting a specific chapter or section from a long audiobook, splitting a multi-hour audiobook into smaller segments, removing unwanted intros, credits, or advertisements, creating audio samples or previews from audiobook content, and reducing file size by removing unnecessary portions.

M4B Audiobook Bitrate Guide

Bitrate	Quality	File Size (per hour)	Best For
32 kbps	Acceptable	~14 MB	Single narrator, voice-only
64 kbps	Good (standard)	~28 MB	Audiobooks (recommended)
96 kbps	High	~42 MB	Audiobooks with music/effects
128 kbps	Very High	~56 MB	Full production audiobooks

Common Cut Scenarios

Goal	Start Time	Duration
Extract Chapter 3 (starts at 45 min)	00:45:00	00:30:00
Remove 2-minute intro	00:02:00	(remaining length)
Create 1-minute preview	00:05:00	00:01:00

How do I find chapter timestamps?

Play the M4B file in iTunes, Apple Books, or VLC to identify chapter start times. Note the timestamps, then enter them as Start Time and Duration in the Trim section.

Will cutting preserve bookmarking?

The cut M4B file retains the M4B format, so audiobook players will still recognize it as an audiobook with bookmarking support. However, the original chapter markers may not be preserved — the cut segment starts as a new file.

What bitrate should I use?

64 kbps AAC is the standard for spoken-word audiobooks — clear voice quality at roughly 28 MB per hour. Use 32 kbps for maximum compression or 96-128 kbps if the audiobook includes music or sound effects.

What is the difference between Cut and Trim?

On XConvert, "Cut" and "Trim" both extract a segment using Start Time and Duration. The Trim M4B page provides the same functionality.

Can I cut and compress at the same time?

Yes. Set cut points under Trim, then choose a compression method under File Compression. Both are applied in a single pass — useful for extracting a chapter and reducing its file size simultaneously.