FLAC to M4B Converter
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Supports: FLAC
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Need help?How to Convert FLAC to M4B
- Upload Your FLAC File — Click "Choose Files" or drag and drop your FLAC audio file. Only .flac files are accepted.
- 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.
- 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.
- Trim (Optional) — Under Trim, set a Start Time and Duration in seconds or HH:MM:SS.sss format.
- Convert & Download — Click "Convert" and download your M4B file.
Why Convert FLAC to M4B?
FLAC is a lossless audio format — perfect quality but large files (30-50 MB per song). M4B (MPEG-4 Audio Book) is Apple's audiobook format with bookmarking and chapter support. Converting FLAC to M4B is ideal for turning lossless audiobook recordings into Apple Books-compatible files, creating audiobooks from FLAC concert or lecture recordings with resume playback, preparing high-quality spoken-word content for iTunes audiobook library, and converting lossless podcast archives into bookmarkable audiobook format.
Starting from FLAC ensures the best possible M4B output since no quality was lost in the source.
FLAC vs M4B Comparison
| Feature | FLAC | M4B (Audiobook) |
|---|---|---|
| Compression | Lossless | Lossy (AAC) |
| File size (1 hr) | ~300-500 MB | ~28-56 MB |
| Bookmarking | No | Yes (resume playback) |
| Chapter markers | No | Yes |
| iTunes category | Music | Audiobooks |
| Best for | Archival, audiophile | Audiobooks, podcasts |
Recommended Bitrates
| Bitrate | Quality | File Size (per hour) | Best For |
|---|---|---|---|
| 64 kbps | Good (standard) | ~28 MB | Audiobooks |
| 96 kbps | High | ~42 MB | Music/effects |
| 128 kbps | Very High | ~56 MB | Full production |
Will converting FLAC to M4B lose quality?
Yes — M4B uses lossy AAC compression. However, starting from lossless FLAC ensures the best possible AAC output. At 128 kbps AAC, the quality is virtually indistinguishable from the FLAC source for spoken-word content.
What bitrate should I use?
64 kbps AAC is the standard for spoken-word audiobooks. Use 96-128 kbps if the content includes music or sound effects. Starting from FLAC, even 64 kbps produces excellent results.
What is the difference between M4B and M4A?
Both use AAC codec in MPEG-4 container. M4B tells media players to enable audiobook features (bookmarking, chapters). iTunes categorizes M4B under Audiobooks.
Can I trim the audio during conversion?
Yes. Under Trim, switch to "Trim" and enter a Start Time and Duration. Useful for splitting a long FLAC recording into chapters.
Does M4B work on Android?
Android doesn't natively support M4B bookmarking. Apps like Smart AudioBook Player and VLC can play M4B with chapter support.