audiobook-length

Estimate how long a book takes to listen to at a given narration pace and playback speed. You can start from a word count, a page count, a text file, or an EPUB that isn't copy-protected.

The formula and rounding match the CocoReader audiobook length calculator: listening minutes are words ÷ (narration wpm × speed). CocoReader: Book to Audiobook is the iOS app this tool sits beside.

This package does not synthesise speech. It only estimates time.

Install

pip install audiobook-length

Defaults

These are the same assumptions as the site calculator:

155 wpm is a common industry estimate for narrated audiobooks (roughly 9,300 words per finished hour). Silent reading defaults follow Brysbaert (2019). Times longer than an hour are rounded to the nearest five minutes; shorter times to the nearest minute. A 90,000-word novel is 9 h 40 m at 1× and 4 h 50 m at 2×.

Catalog word counts on the CocoReader site are rounded to the nearest thousand before they are shown. This package exposes round_words_to_nearest_thousand for that, and leaves raw counts alone unless you call it.

Usage

from audiobook_length import estimate, format_duration, words_from_epub

result = estimate(words=90_000)
print(format_duration(result.listening_minutes))
# 9 h 40 m

result = estimate(pages=300, words_per_page=275, speed=1.5)
print(format_duration(result.listening_minutes))
# 5 h 55 m

result = estimate(text="Call me Ishmael. Some years ago...")
result = estimate(epub="book.epub", speed=1.25)

Or from the command line:

audiobook-length --words 90000
audiobook-length --pages 300 --speed 1.5
audiobook-length --text-file chapter.txt --wpm 160
audiobook-length --epub book.epub --speed 1.25

Word counts from text and EPUB

Text is split on whitespace. That is a simple count, not the tokenizer CocoReader uses when it reads a book aloud, so hyphenated words, footnotes, and drop caps may not match the app.

An EPUB is opened as a zip, the spine is read from the package document, and the visible text is taken from each spine item. Copy-protected EPUBs are not supported. Files that cannot be opened raise EpubError.

License

MIT. Copyright 2026 Philip Daquin.