Change Speed
Audio Processing LaboratorySpeed up or slow down audio without wrecking the pitch.
What is Change Speed?
Change Speed makes an audio file play faster or slower without shifting its pitch, so voices and music stay natural. Drop in a file and set a speed between 0.5x and 2x. The work is done by in-browser FFmpeg (WebAssembly) using its atempo filter, so your audio is processed on your device and never uploaded.
How to use Change Speed
Add your audio
Drag an MP3, WAV, or other audio file onto the drop zone. The in-browser FFmpeg engine begins loading in the background and a status line shows its progress.
Set the speed
Drag the speed slider between 0.5x (half speed) and 2x (double speed). 1.00x leaves the audio unchanged, and the pitch is preserved at every setting.
Change speed
Click Change speed once the engine is ready. A percentage indicator shows the processing progress while FFmpeg re-times the audio.
Preview and download
Play the result to check it, then click Download to save the WAV. Everything runs locally, so nothing is uploaded.
Common uses
- Speed up a lecture or podcast to get through it faster
- Slow down a fast passage to transcribe it accurately
- Slow music to learn a solo or vocal line note by note
- Tighten the timing of a voiceover to fit a set length
- Slow a language recording to catch every word
- Pace-match narration to a video edit
Why choose FreeTools
100% private
Your files are processed inside your browser and are never uploaded to a server.
Free, no account
No sign-up, no watermark, no paywalled “premium” tier. Just open a tool and use it.
Instant
No upload, no queue, no server round-trip — work starts the moment you drop a file.
Runs in your browser
Built on open web standards. Works on any modern desktop browser, nothing to install.
No upload size caps
Nothing leaves your device, so there’s no server file-size limit — only your machine’s memory.
Yours to keep
Results download straight to your device in clean, standard file formats.