Audiobook mastering service

Audiobook Mastering for Your Whole Book

Recorded your audiobook yourself, or had it narrated, and need it mastered to the audio specs retailers ask for? Upload every chapter at once and we master the entire book in one go, at a flat price set by its length.

  • Even loudness: each chapter's average level is set between -23 and -18 dB RMS.
  • Safe peaks: peaks are kept under -3 dB.
  • Correct format: 44.1 kHz, mono, 192 kbps constant bit-rate MP3.
  • Room tone: clean silence at the start and end of every chapter (about 0.6 seconds in, 3 seconds out).

Not sure your files need it? Start with the free audiobook spec checker: it tests one chapter and tells you what fails.

Total audiobook lengthPrice
Up to 1 hour $19
1–3 hours $39
3–6 hours $59
6–10 hours $79
10–15 hours $89
15–20 hours $99

Over 20 hours? Email us for a custom quote.

How it works

  1. Upload your complete audiobook: a ZIP of MP3 chapters, or all the MP3s selected at once.
  2. We measure the total run-time and show your exact price before you pay.
  3. Pay securely by card and download your mastered chapters, in the same order.

A free AuthorVoices account is needed when you upload, so your files and download stay private to you.

Upload your audiobook

ZIP of MP3 chapters, or a single MP3. We'll price it before you pay.

Priced by length
ACX does not allow AI narration, but typically overlooks AI-generated opening and closing credits when the rest of the book is human-narrated. Use these files at your own risk — they're included in this service. The AI may not pronounce every name perfectly; you can regenerate them anytime by submitting again.
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