About the Audio Speed Changer
Speed up or slow down any audio file without the chipmunk effect: lectures and podcasts at 1.5× to save time, a song at 0.75× to learn a guitar part, a language lesson at 0.5× to catch every word. Choose the file and the speed, and download the new version.
The pitch stays the same, so voices sound natural at any speed from 0.5× to 3×. The change is made in your browser, so the file is never uploaded, up to 100 MB.
How it works
Simply playing samples faster would also raise the pitch, like a record spun too fast. Instead, the audio is time-stretched: it is cut into tiny overlapping pieces that are spaced closer together or further apart, which changes the length while every note keeps its frequency.
The new length is the old length divided by the speed: a 30-minute podcast at 1.5× takes 20 minutes, and at 2× takes 15. The stretching filter works between half and double speed in one step, so 3× is made as 2× followed by 1.5×.
The result is saved in the original format when it can be written, or as MP3, and can be listened to on the page before downloading.
Assumptions and limits
- Speeds from 0.5× to 3×, in any step such as 1.25× or 1.1×.
- Lengths can differ from the exact figure by a few hundredths of a second, as the stretching works in small blocks.
- Very fast speech above 2× stays clear for most voices; music can sound choppy at extreme speeds.
Worked examples
A lecture at 1.5×
A 60-minute recorded lecture becomes 40 minutes, with the lecturer's voice at its normal pitch.
Practising a song at 0.75×
A 4-minute song becomes 5:20, slow enough to follow a solo, and still in the same key.
Shortening a voice message
A 3-minute voice note at 2× becomes 1:30.
How to use the Audio Speed Changer
- Upload the recording. Song, lecture, podcast or voice note.
- Choose a new speed. From 0.5× slower to 3× faster.
- Download at the new pace. Same pitch, new length.
Frequently asked questions
How do I speed up audio without changing the pitch?
Choose the file, pick a speed such as 1.5× and press Change the speed. The audio is time-stretched rather than played faster, so it gets shorter while voices and notes keep their original pitch.
How long will the audio be at the new speed?
Divide the original length by the speed. A 45-minute file at 1.5× lasts 30 minutes, at 2× lasts 22.5 minutes, and at 0.75× lasts 60 minutes. The page shows this for a 10-minute file as you change the speed.
Can I slow down a song to learn it?
Yes. Choose 0.75× or 0.5× and the song plays slower in the same key, so you can play along on your instrument. For practice at the same speed in another key, use the pitch shifter instead.
What speeds can I choose?
Any speed from 0.5× (half speed, twice as long) to 3× (three times as fast). The buttons give common speeds, and you can type others, such as 1.25× or 1.1× for a small change.
Does changing the speed reduce the quality?
Time-stretching is done carefully, but at large changes some smearing or a slight echo can be heard, mostly in music. Speech at 1.25× to 2× usually sounds natural. Saving as WAV avoids any extra compression.
This tool runs entirely in your browser. What you enter or upload stays on your device and is never sent to our servers.