Audiobook speed calculator

Listening time by playback speed

A 10 hr audiobook at common speeds.

Prefer print? Estimate how long the book takes to read at your reading speed. Recording your own narration? Work out speaking time from a word count.

How to use the audiobook speed calculator

The calculator has two tabs. Speed plans a book before you press play, and Progress shows where you stand once you have started. Playback speed and minutes per day sit below the tabs and apply to both.

1. Open the Speed tab and enter the audiobook's length in hours and minutes, as your app or store lists it. No length yet? Choose Words and enter the word count instead.
2. Tap a speed (1.25×, 1.5×, 1.75× or 2×), or set any speed from 0.5× to 3.5× with the slider or the number field.
3. Tap the minutes you listen per day, or type your own number. The calculator starts at 30 minutes.
4. Read your listening time and the time you save, then your finish date and how many books of this length fit in a year. The table under the result compares your book at speeds from 1× to 3×.
5. Copy the result, or copy a link that opens the calculator with your length and speed filled in. Your last entries also stay in this browser for your next visit.

Partway through a book, switch to the second tab.

1. Open the Progress tab and enter the book's total length.
2. Enter the time listened as the position your player shows, in hours and minutes.
3. Read the percent complete and the time left, shown at 1× and at your playback speed.
4. Check the finish date and the speed table below, which now count only the part you have left.

The finish date counts today as your first listening day, so a book that fits in one day finishes today.

How long is an audiobook from its word count

Most narrators read about 9,300 words per hour, according to ACX's guide to audiobook length. That rate equals 155 words per minute (WPM). A 2019 review of reading rate by Marc Brysbaert puts audiobook narration at 140 to 180 WPM, and the ACX figure sits inside that range.

Use word count over page count when you have it, because pages shift with font size and layout from one edition to the next. Narrators vary too, and a slow, dramatic reading runs longer than the estimate. When the store lists the finished length, enter those hours in the calculator instead.

Divide the word count by 9,300 for hours at 1×, then divide by your speed: 100,000 words at 1.5× comes to about 7 hours 10 minutes.

Audiobook narration at 1× vs your reading speed

At 1×, narration runs slower than most adults read in silence. ACX's 9,300 words per finished hour comes to 155 words per minute (WPM), and Brysbaert's meta-analysis of 190 studies puts the average adult silent reading rate in English at 238 WPM for non-fiction and 260 WPM for fiction. At those averages, reading the text takes 35% to 40% less time than listening at 1×.

Playback speed multiplies the narrator's rate. A narrator at 155 WPM reaches about 194 WPM at 1.25×, about 233 WPM at 1.5×, about 271 WPM at 1.75× and 310 WPM at 2×. The table in the calculator lists this rate for every speed.

Brysbaert's review places most adults between 175 and 300 WPM for non-fiction. At 2×, narration (310 WPM) passes the top of that range.

Your own rate makes a better reference than the average. Find your own words per minute, then divide that number by 155 to find the playback speed that matches your reading pace. A reader at 300 WPM, for example, matches about 1.9×.

At 1.5×, a 155 WPM narrator plays at 232.5 WPM, within 6 WPM of the average adult reading non-fiction in silence.

Comprehension at 2× speed: what a lecture study found

Murphy, Hoover, Agadzhanyan, Kuehn and Castel (2022) tested 231 UCLA undergraduates on two lecture videos, one on real estate appraisals and one on the history of the Roman Empire. Each ran 13 to 14.5 minutes at 1×, with slides beside the lecturer. Students watched at 1×, 1.5×, 2× or 2.5× without pausing or taking notes, then answered 20 questions right after each video and a second set one week later.

Scores at 1.5× and 2× did not differ in a reliable way from scores at 1×. The 1× group did score higher than the 2.5× group, 65% correct against 55% on the immediate test and 59% against 50% a week later. No other pair of speeds differed. Speed and test timing did not interact, so the delay did not change how the speeds compared. At 2×, the two videos ran at 314 and 332 WPM, close to a 155 WPM narrator at the same setting.

A second experiment compared watching a video twice at 2× with watching it once at 1×. Scores came out level (64% for once at 1×, 63% for twice at 2×). In a follow-up, students who watched at 2× and rewatched at 2× right before a test one week later scored higher than students who watched once at 1× a week before the test.

Two caveats carry over to audiobooks. The authors point out that still slides do not change with playback speed, so viewers can take in that content even when speech gets harder to follow. An audiobook gives you the voice alone. They also note that their results may differ for other speech rates or harder material.

In the lecture study, scores at 2× showed no reliable drop from 1×, and scores at 2.5× did. With no slides to fall back on, check your own recall before you settle above 1.5×.

How to choose an audiobook playback speed

Start at 1.25×, which cuts a 10-hour book to 8 hours and puts a 155 WPM narrator at about 194 WPM, then adjust with the checks below.

• Raise the speed in steps of 0.1× to 0.25×, and give each step a full chapter before you judge it.
• After each chapter, summarize it in two sentences. If you can't, drop back one step.
• Slow down for dense non-fiction, unfamiliar names or terms, heavy accents and narration where delivery carries meaning, such as drama or poetry.
• Speed up for material you already know, such as a re-listen or a topic from your own field.

For context, 60% of the 123 students in the comparison group of the UCLA study named 1.5× as their usual speed for recorded lectures, and 23% named 2×. Those answers describe lecture habits. When the study measured comprehension, it assigned each student a speed at random.

Why your app shows a different time remaining

This calculator and your player can both be right and still disagree. Run through these checks before you trust either number.

• Book time or listening time. A remaining time can count the book at 1× or the minutes you will spend at your speed. The Progress tab shows both. Spotify counts the audiobook listening time in its Premium plans at normal speed: a 5-hour audiobook at 2× uses 5 hours of that time, even though you finish in 2 hours 30 minutes.
• Book or chapter. Libby shows the remaining time in the audiobook at the top of the player and the time left in the current chapter beside the chapter name. Enter the figure for the whole book.
• Speed steps. Audible offers 0.5× to 3.5× in steps of 0.1×, and Libby takes a custom speed from 0.6× to 3× on its Fine-tune slider. Type the exact speed your player shows, such as 1.3×, instead of the nearest chip.
• Rounding. The calculator rounds to whole minutes. If your player shows seconds, a gap of a minute comes from rounding alone.

Change the speed in your app and watch the remaining time. If it stays the same, your app counts book time: enter your position on the Progress tab to see the listening time at your speed.

Tracking a long audiobook

Minutes per day turn a long book into a schedule. A 12-hour book at 1.5× takes 8 hours of listening, so at 30 minutes a day you finish in 16 days. At 1×, the same habit takes 24 days.

Partway through, the Progress tab gives you a checkpoint. Enter 12 hours as the total and 4 hours 30 minutes as your position, and you are 37.5% through with 7 hours 30 minutes of book time left. At 1.5×, that is 5 hours of listening, or ten 30-minute sessions.

Add the book to the reading tracker to keep it on your list beside your print books, and mark it finished when you are done. To compare with reading the print edition, the book reading time calculator estimates reading time from your WPM.

How many audiobooks a year at your pace

Multiply your minutes per day by 365, then divide by the listening time of one book at your speed. The calculator shows the result as Books of this length a year, for the book you entered.

At 30 minutes a day, you listen for 10,950 minutes a year, or 182.5 hours. A 10-hour book at 1.5× takes 6 hours 40 minutes, so that habit covers about 27 books of that length. At 1×, the same habit covers about 18.

With only a word count, start from ACX's 9,300 words per finished hour. A 100,000-word book runs about 10 hours 45 minutes at 1× and about 7 hours 10 minutes at 1.5×, which gives about 25 books a year at 30 minutes a day.

Books a year = minutes per day × 365 ÷ (book length ÷ speed). Going from 1× to 1.5× fits 50% more books into the same daily habit.

Questions

Sources

1. ACX (n.d.), How long will my narrated audiobook be?, ACX Help Center
2. Brysbaert (2019), How many words do we read per minute? A review and meta-analysis of reading rate, Journal of Memory and Language 109
3. Murphy, Hoover, Agadzhanyan, Kuehn and Castel (2022), Learning in double time: The effect of lecture video speed on immediate and delayed comprehension, Applied Cognitive Psychology 36(1)
4. Audible (n.d.), Narration speed, audible.com
5. Libby Help (n.d.), Changing playback speed, OverDrive
6. Libby Help (n.d.), Viewing your progress in an audiobook, OverDrive
7. Spotify Support (n.d.), Audiobooks in Premium plans