Audiobook Calculator and Reading Time Calculator

This audiobook calculator tells you how long a recording really takes at the playback speed you listen at, and how much time that saves against normal speed. It is also a reading time calculator: enter a word count and a reading speed, and it gives the time to read it, which is useful for essays, articles, speeches and books.

Playback speed is simple division, but it trips people up because the saving is not proportional to the speed. Listening at 2× halves the time, but 1.5× does not save half as much as 2×; it saves a third of the length. The table on this page lists a 10 hour book at every common speed so you can see where the gains flatten out.

For reading, the default speed is 238 words per minute. That is the average silent reading rate for adults reading English non-fiction, from a 2019 review of 190 studies by Marc Brysbaert. The same review puts fiction at 260 words per minute and reading aloud at 183. Your own speed may be well above or below any of these, so treat the default as a starting point and change it.

1. Choose Audiobook time at a playback speed or Reading time from a word count.
2. For an audiobook, enter its length in hours and minutes, as the store or app lists it, and your Playback speed.
3. For reading, enter the Word count and your Reading speed in words per minute.
4. Read the time to finish at the top. The cards show both calculations, the audiobook time in minutes, and how much time the playback speed saves or adds.

The presets load a 10 hour book at 1.5×, a 12 and a half hour book at 2×, a slow 0.8× listen, a 5,000 word essay, and a 1,500 word speech read aloud.

1. Audiobook length in minutes. The hours are converted to minutes, 60 to the hour, and the minutes added.

1. Listening time. The length is divided by the playback speed.

1. Time saved. The listening time is subtracted from the length at normal speed. Above 1× the difference is time saved; below 1× it is time added.

1. Reading time. The word count is divided by the reading speed in words per minute.

1. Display. Times are rounded to the nearest second, half up, and written in hours, minutes and seconds. The minute cards show one decimal place.

A 10 hour audiobook at 1.5×, the default:

1. 10 hours is 600 minutes.
2. 600 ÷ 1.5 = 400 minutes, which is 6 hr 40 min.
3. 600 − 400 = 200 minutes, so the speed saves 3 hr 20 min.

A 12 hr 30 min book at 2× takes 6 hr 15 min, saving the same again. An 8 hour book at 0.8× takes 10 hr, which adds 2 hr.

Reading 5,000 words at 238 words per minute takes 5,000 ÷ 238 minutes, just over 21, shown as 21 min 1 s. A 1,500 word speech read aloud at 183 words per minute takes 8 min 12 s.

Two thirds of its length. Dividing by 1.5 is the same as multiplying by two thirds, so a 10 hour book takes 6 hr 40 min. At 1.25× a 10 hour book takes 8 hr, and at 2× it takes 5 hr.

About 4 minutes at the average silent reading speed: 1,000 words at 238 words per minute is 4 min 12 s. The words to minutes table below runs from a 250 word note to a 100,000 word book, which takes 7 hr 0 min 10 s at the same speed.

• Your own reading speed. Speeds vary widely between people and between texts. Most adults read English non-fiction silently at somewhere between 175 and 300 words per minute. Time yourself on a page and enter your own figure.
• Difficulty and attention. Technical text, a second language or study reading are slower than the averages here. Skimming is faster.
• Pitch-corrected speed limits. Apps differ in the speeds they offer and in how they round them. The calculator uses the number you enter.
• Breaks and rewinds. The times are continuous listening or reading. Pauses, re-listening and note taking add to them.
• Narrator pace. Two audiobooks of the same text can differ in length because narrators read at different speeds. Use the length the app shows for your edition.

• Thinking 1.5× saves half the time. It saves a third. Only 2× halves the time.
• Typing 10.30 for 10 hours 30 minutes. In the hours box, 10.30 means 10.3 hours, which is 18 minutes past the hour, not 30. Enter 10 and 30 in their own boxes.
• Using a pages figure as words. Pages vary a great deal in how many words they hold. If you only know pages, count the words on a typical page and multiply first.
• Comparing silent and spoken speeds. Reading aloud is slower than reading silently, so time a speech at a speaking rate.
• Over-trusting the average. 238 words per minute is the middle of a wide range, not a target.

• Brysbaert, M. (2019). How many words do we read per minute? A review and meta-analysis of reading rate. Journal of Memory and Language, 109, 104047. doi.org/10.1016/j.jml.2019.104047
• NIST Special Publication 811, Guide for the Use of the International System of Units, Chapter 5, Table 6: the minute and hour accepted for use with the SI. nist.gov/pml/special-publication-811/nist-guide-si-chapter-5-units-outside-si