Audiobook Speed Changer: save at 1.5× or 2×

Where it runs

Works in a current Chrome, Edge, Firefox or Safari, on Windows, Mac, Linux and Chromebook computers, Android phones, iPhones and iPads. Nothing to install, no account.

The first file loads the audio engine (ffmpeg, about 31 MB) once, and your browser keeps it. Very long books are easiest on a computer, which has more memory than a phone.

4 simple steps.

Drop your audiobook

M4B, MP3, M4A, FLAC, WAV, OGG or Opus. Its length and chapters are read at once.

Choose a speed

Anything from 0.5× to 3×. The new length and the time saved update as you slide.

Hear it first

Listen at the new speed before converting; the voice keeps its natural pitch.

Download

A new file that plays at that speed everywhere, with its chapters moved to match.

Changing speed without changing pitch

Playing a recording faster, like a tape, raises its pitch: that is the chipmunk effect. Instead, the speed changer cuts the audio into very short overlapping slices and lays them closer together (or further apart), so the tempo changes while every voice keeps its own pitch.

How much time you save

Speed	A 10-hour book becomes	Time saved
1.25×	8 h	2 h
1.5×	6 h 40 min	3 h 20 min
1.75×	5 h 43 min	4 h 17 min
2×	5 h	5 h

Want the numbers for your own book first? The speed calculator works it out for any length and speed.

Questions, answered.

How do I speed up an audiobook file?

Drop the file here, pick a speed such as 1.5×, and press the button. The audio is stretched in time without changing its pitch, so voices still sound natural, and the chapter marks are moved to the new times.

Why not just use my player’s speed setting?

Many devices have none: car stereos, some smart speakers, older MP3 players and some apps. A file saved at the new speed plays faster everywhere.

Will the voice sound like a chipmunk?

No. Pitch is kept as the tempo changes, the same way audiobook apps do it. Very high speeds (above about 2.5×) start to sound clipped, as they do in any app.

Can I slow an audiobook down?

Yes. Speeds down to 0.5× work too, useful for language learners or to follow dense material.

What happens to the chapters?

They are kept and moved: a chapter that started at 1 hour starts at 40 minutes in a 1.5× file.

Is my file uploaded?

No. The file is processed in your browser and never leaves your device.