BYTETOOLS

Change Audio Speed

Change audio speed online for free. Speed up or slow down audio from 0.5x to 2x without changing pitch, exported as MP3 — nothing is ever uploaded.

Drop an audio file here or click to browseYour audio is processed locally and never uploaded.

What is the Change Audio Speed?

The ByteTools Change Audio Speed tool speeds up or slows down any audio file while keeping the pitch natural, then exports the result as an MP3.

  • Speed range from 0.5x to 2x
  • Pitch preserved so voices sound natural
  • Exports the adjusted audio as MP3
  • 100% local — audio is never uploaded
  • Built-in preview player before download
  • Free, unlimited and works offline once loaded

How to use the Change Audio Speed

  1. 1

    Drop an audio file onto the box or click to browse for one.

  2. 2

    Set the playback speed with the slider (0.5x to 2x).

  3. 3

    Click Change Speed and wait for the in-browser engine to finish.

  4. 4

    Preview the result, then download your new MP3.

About the Change Audio Speed

The ByteTools Change Audio Speed tool speeds up or slows down any audio file while keeping the pitch natural, then exports the result as an MP3. Drop in a file, pick a speed from 0.5x to 2x, and ffmpeg's atempo filter does the rest.

Slowing audio down helps with transcription, language practice and learning music by ear, while speeding it up is handy for getting through lectures, audiobooks and voice notes faster. Because the pitch is preserved, voices do not sound squeaky or deep.

Everything runs entirely in your browser using a WebAssembly build of ffmpeg. Your audio never leaves your device — no uploads, no server, no account — so your files stay private, and the tool keeps working offline once loaded.

Frequently asked questions

Does changing speed change the pitch?

No. This tool uses time-stretching (the atempo filter), which changes the tempo while keeping the pitch the same, so sped-up voices do not sound high-pitched and slowed-down audio does not sound deep.

Why is the speed limited to 0.5x–2x?

The atempo filter is designed to preserve quality within the 0.5x to 2x range. Staying inside this range keeps the pitch-corrected result clean and avoids audible artifacts.

What is a good speed for studying or transcription?

For transcription and language learning, 0.7x to 0.9x makes speech easier to follow. For getting through lectures or audiobooks faster, 1.25x to 1.5x is comfortable for most listeners.

Is my audio uploaded to a server?

No. The processing runs entirely in your browser using WebAssembly, so your file is handled on your own device and never uploaded.

Which browsers are supported?

In-browser processing needs a modern desktop browser such as Chrome, Edge or Firefox. Because everything runs locally, large files take longer and use more memory.

Guides for Change Audio Speed

Related tools