M4B to WMA Converter

Convert M4B to WMA: What This Tutorial Covers

This walks through turning a DRM-free .m4b audiobook into a .wma file for an older Windows Media-era device or player that specifically demands that extension. It also covers the two things that surprise people most: the chapter list and resume position do not carry over, and DRM-protected store purchases can't be converted at all. If your goal is modern, broad playback rather than one legacy device, M4B to MP3 is the better target.

How to Convert M4B to WMA

1. Upload Your M4B File: Drag and drop your .m4b onto the page or click "Add Files." Audiobooks often ship as several part files — queue them all and they run with the same settings.
2. Pick a Quality Preset: Open the Preset dropdown (Highest down to Lowest) to trade size against fidelity. For spoken-word audiobooks the upper presets are overkill; switch to Custom Bitrate and type 64 kbps for voice, or 96–128 kbps if the book has music beds or full dramatization.
3. Set Audio Channel and Sample Rate (Optional): Leave Audio Channel on Original, or pick Mono for voice-only books to roughly halve the bitrate. Leave Audio Sample Rate on Original; the standard WMA codec caps at 48 kHz, so there's nothing to gain by raising it.
4. Convert and Download: Click Convert and save the .wma. No sign-up, no watermark.

Walk-through: Choosing a Bitrate for a Long Audiobook

Audiobooks run for hours, so the bitrate you pick is the single biggest lever on the output file size — a 20-hour book at 128 kbps is roughly four times the size of the same book at 32 kbps. Because M4B carries AAC and WMA is a different lossy codec, the conversion is a re-encode (AAC decode to PCM, then WMA encode); it can never add detail back, so the goal is to match or slightly exceed the source bitrate, not to crank it past the source and waste space.

• Voice-only narration: Custom Bitrate at 64 kbps, Audio Channel Mono. This is the long-standing spoken-word default and keeps a long book manageable.
• Music beds or sound design between chapters: 96–128 kbps, keep Stereo.
• Full-cast audio drama: 128 kbps Stereo; the standard WMA codec tops out near 192 kbps, so that is the practical ceiling for fidelity.
• Storing many books on a small device: 32 kbps Mono trades audible sibilance for size — only worth it when capacity is the hard constraint.

To check the source bitrate, look at the M4B's file properties; if it reports, say, 64 kbps AAC, encoding to 128 kbps WMA buys nothing but a bigger file.

Common Errors and How to Fix Them

• "My chapters are gone and it plays as one long file" — Expected. WMA's ASF container has no audiobook chapter track, so chapter markers and the resume/bookmark position do not survive. The audio plays start-to-finish as one continuous file. To split it back into navigable parts, run Audio Cutter on the WMA at the timestamps you want.
• "The converter rejects my file or errors out" — The most common cause is DRM. Audiobooks bought from the iTunes Store or Apple Books are wrapped in Apple's FairPlay protection, and online converters cannot decrypt them. Only DRM-free .m4b files convert.
• "The .wma won't play on my phone or in my browser" — WMA is mainly a Windows and Windows Media Player format. Most phones, Apple devices, and many modern browsers do not decode it. If the file needs to play broadly, convert to M4B to MP3 instead and reserve .wma for the one device that requires it.
• "The audio sounds worse than the original" — You went through a lossy-to-lossy re-encode. Keep the output bitrate at or above the source bitrate, and use Variable Bitrate where available to minimize the loss.
• "A 20-hour book is taking a while to upload or encode" — Long-duration files are large and take proportionally longer to upload and process; that is upload time and encode duration scaling with length, not an error. Let it finish.

When This Doesn't Work

WMA is a legacy target, so this conversion only makes sense when something genuinely requires a .wma file — an old in-car head unit, a pre-2010 Windows Media-era player, or a Windows Media Player library that expects that extension. If you mainly want a converted audiobook that plays on modern phones, cars, and apps, M4B to MP3 is the standard escape and plays almost everywhere. And if the source is a DRM-protected store purchase, no online converter can open it; you would need to format-shift through the vendor's own authorized tools first, where your jurisdiction permits it.

Frequently Asked Questions

Will my audiobook keep its chapters after converting to WMA?

No. M4B stores chapters and the resume position in a dedicated track inside its MPEG-4 container; WMA's ASF container has no equivalent, so a multi-chapter audiobook becomes one continuous file with no chapter navigation and no auto-resume. If chapter-style navigation matters, keep the file as M4B, or convert and then cut it into parts with Audio Cutter. For broad playback with the smaller AAC kept intact, M4B to MP3 is the usual pick.

Can I convert a DRM-protected M4B from the iTunes Store or Apple Books?

No. Those purchases are encrypted with Apple's FairPlay DRM, and online converters cannot decrypt them. Only DRM-free .m4b files work. If you have a legal copy and the right to format-shift where you live, you must first remove the DRM through the vendor's own authorized path; xconvert then converts the resulting DRM-free file but never strips DRM itself.

Should I pick WMA v1 or WMA v2?

This converter defaults to WMA v2 (WMAV2), and that is the right choice for almost everyone — it is the standard, more efficient encoder, and because the WMA 2 decoding process is compatible with the original codec, the resulting file plays on any reasonably modern Windows Media stack. WMA v1 is the original 1999 codec; choose it only if you are feeding a very old device that predates v2 support.

Why would I convert an audiobook to WMA instead of MP3?

Almost the only good reason is a device or program that specifically demands .wma. WMA is a Microsoft format that first shipped in 1999 and is decoded mainly by Windows and Windows Media Player; MP3 plays on practically every car stereo, phone, and player ever made. Unless an old Windows-era device forces your hand, M4B to MP3 is the more compatible audiobook conversion.

What bitrate should I use for a spoken-word audiobook?

64 kbps mono is the long-standing default for voice — it fits narration comfortably and keeps a long book manageable. Drop to 32 kbps mono only when you are squeezing many books onto a small device and can tolerate audible compression on "s" and "sh" sounds. Step up to 96–128 kbps stereo if the book includes music between chapters or full audio-drama production. In our testing, a one-hour voice-only M4B at 64 kbps mono produced a WMA of roughly 28–30 MB.

How are my uploaded audiobook files handled?

Files are uploaded over an encrypted connection, processed on our servers, and deleted automatically a few hours after conversion. There is no sign-up, no watermark, and your files are never shared or made public. With a long audiobook, the main wait is upload and encode time, which scale with the length of the file rather than any per-file size cap.