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Convert M4B to OGG Online — Open Source Format

Convert M4B audiobooks to open-source OGG Vorbis for free software players.

Drop up to 50 files at once — no install, no sign-up required.

Drop M4B Files Here

50 MB or 2 hours per file Up to 50 files 3 parallel conversions 1 credit per 5 minutes

Encrypted EU Servers Auto-delete 1h

⚡ Median M4B → OGG time (last 10k jobs): 335ms per minute

How it works

  1. 1 · Drop your files

    Drag & drop or choose M4B files. No account required—paid plans unlock bigger batches, higher limits, and priority queues.

  2. 2 · We convert securely

    Processed on our dedicated servers. Encrypted in transit & at rest. We never store filenames—only file types & sizes for accounting.

  3. 3 · Download & auto-delete

    Grab your OGG files in seconds. Files delete automatically after 1 hour. Delete anytime after downloading with one click.

About M4B →

M4B is Apple's audiobook format, essentially an M4A file with chapter markers and bookmark support. Introduced with iTunes in 2003, M4B uses AAC audio encoding in an MPEG-4 container—the same codec as M4A—but with additional metadata for chapter navigation and resume-position bookmarks. This makes M4B ideal for long-form audio content like audiobooks and podcasts. Files from Audible (after DRM removal), iTunes Store, and Librivox commonly use M4B format.

Learn more: M4B on Wikipedia

M4B supports sample rates up to 96 kHz and multi-channel audio, though most audiobooks use mono or stereo at 44.1 kHz for efficiency. The chapter markers embedded in M4B files enable navigation to specific sections—a feature lost when converting to formats like MP3 or WAV. For maximum compatibility with car stereos, older MP3 players, and non-Apple devices, converting M4B to MP3 is often necessary. For archival or editing, WAV extraction provides lossless quality.

About OGG →

OGG (Ogg Vorbis) is an open-source, royalty-free lossy audio codec developed by the Xiph.Org Foundation, with Vorbis 1.0 finalized in July 2002 as a patent-free alternative to MP3. Technically, "Ogg" is the container format while "Vorbis" is the audio codec, but "OGG" commonly refers to Vorbis-encoded audio files. Vorbis achieves compression ratios of 8:1 to 10:1 using a quality scale from -1 (lowest) to 10 (highest), and generally outperforms MP3 in blind listening tests at equivalent bitrates—particularly at 128 kbps and below.

Learn more: Vorbis on Wikipedia

OGG supports sample rates up to 192 kHz and up to 255 audio channels, making it technically versatile. Its main strength is open licensing—it's the standard audio format for video games (Unity, Unreal Engine), Spotify's internal format, and widely used in open-source software. The tradeoff is hardware support: while software players universally support OGG, many hardware devices (car stereos, standalone MP3 players) do not. For gaming audio, podcasts in open-source ecosystems, or any project avoiding patent concerns, OGG is the pragmatic choice.

Frequently Asked Questions

What is the difference between M4B and OGG?

M4B is Apple's proprietary audiobook format using AAC encoding with chapter markers. OGG Vorbis is a completely open-source, royalty-free audio format supported by free software. OGG is preferred by Linux users and open-source advocates who want to avoid proprietary formats.

Why convert M4B to OGG instead of MP3?

OGG Vorbis is completely open source and patent-free. Unlike MP3, which has licensing requirements, OGG is free for all uses. At quality level 9 (~320kbps equivalent), OGG provides excellent audio quality with efficient compression. If you prefer universal compatibility, try M4B to MP3 instead.

Will converting M4B to OGG preserve audiobook chapters?

Chapter markers are not preserved in standard OGG Vorbis format. M4B files contain iTunes-style chapter metadata that doesn't map directly to OGG. If you need chapters, consider keeping your original M4B files alongside the OGG versions for archival purposes.

What OGG quality settings do you use?

We encode at quality level 9 using the Vorbis encoder, which produces files equivalent to ~320 kbps bitrate. This provides excellent audio quality—the highest practical setting for most content. OGG uses variable bitrate (VBR) encoding, so actual bitrates vary based on audio complexity.

How does OGG quality compare to M4B?

At quality level 9, OGG Vorbis provides excellent quality exceeding typical M4B audiobook encoding (usually 64-128 kbps AAC). Since M4B is already lossy compressed, converting to OGG will introduce minimal additional quality loss. For completely lossless output, use our M4B to WAV converter instead.

What devices and players support OGG?

OGG has excellent support on Linux, Android, and in web browsers. VLC, Firefox, Chrome, and most open-source media players handle OGG natively. However, Apple devices (iPhone, iPad) and some car stereos don't support OGG without third-party apps. Check your target device before converting.

How long can my audiobook files be?

Duration limits depend on your plan: Guest/Free: 120 minutes, Pro: 600 minutes (10 hours), Business: 3000 minutes (50 hours). This accommodates everything from short chapters to full-length audiobooks.

What are the limits for this converter?

TierMax File SizeMax Files/BatchParallel Processing
Free50 MB50 files3 at once
Pro500 MB200 files6 at once
Business2048 MB1000 files10 at once

Note: File size limits are specific to this converter. Batch and parallel processing limits apply to all images converters site-wide. See all converter limits →

How are credits calculated for this conversion?

Cost: 1 credit per 5 minutes

How it works:

  • Files up to 5 minutes: 1 credit (minimum)
  • 6-10 minutes: 2 credits
  • 11-15 minutes: 3 credits
  • 16-20 minutes: 4 credits

Example: A 10-minute file = 1 credit. A 180-minute (3h) audiobook = 36 credits.

Why per-minute? Audio conversion time scales with content duration, not file size. Longer audio requires proportionally more processing.

What are my daily and monthly credit limits?

Credit allocations vary by account tier:

TierDaily LimitMonthly Limit
Free50 credits/day—
Pro—10,000 credits/month
Business—30,000 credits/month

Daily credits (Free tier, including guests) reset every day at midnight UTC. Monthly credits (Pro & Business) reset on your billing cycle date.

Note: With 1 credit per 5 minutes, audio files under 5 MB cost 1 credit each. Pro users can convert 10,000 audio files per month.

Answers at a Glance

Quick answers to common questions.

Choose Your Plan

Limits shown for M4B to OGG conversion. One subscription unlocks the entire Tools.FAST Network. Plans cover Convert.FAST, Compress.FAST, PDF.FAST (soon), and all future tools.

Monthly Annual 4 Months Free

Free

$0

For occasional personal use

  • 50 MB per file
  • 50 files per batch
  • 3 parallel conversions
  • 50 credits/day
  • Standard priority
  • Email support
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No sign-up required. Create an account for your own credit pool.

Popular

Pro

$9 /month

For independent work

  • 500 MB per file
  • 200 files per batch
  • 6 parallel conversions
  • 10,000 credits/month across Tools.FAST
  • High priority
  • Email & chat support
  • One subscription for the entire Tools.FAST network

Business

$19 /month

1 seat

For production scale

  • 2 GB per file
  • 1000 files per batch
  • 10 parallel conversions
  • 30,000 credits/month across Tools.FAST
  • Add seats to invite team members
  • Highest priority
  • Priority email & chat support
  • One subscription for the entire Tools.FAST network

How Credits Work

  • Usually 1 credit per conversion. Exact cost shown before you start.
  • Credits refresh monthly on your billing cycle.
  • Unused credits roll over, capped at your plan's monthly amount.
  • One subscription, all sites. Works across Convert.FAST, Compress.FAST, and future tools.
View all converter limits by tier →

What's New in M4B to OGG

Latest improvements to this converter

Last updated December 16, 2025
Dec 16, 2025

Initial release of M4B to OGG converter with high-quality Vorbis encoding.