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Change playback speed

Free online tool to change audio playback speed and export MP3 locally in your browser

Upload audio

Output audio

Choose a file and start processing. The output audio will appear here.

About this tool

Audio speed changes duration and the pace of speech or performance. The selected multiplier produces a new file: 1.25x shortens and 0.75x lengthens it. Processing may attempt to preserve pitch, but extreme rates can still introduce flutter, metallic texture, or blurred articulation.

It suits faster lesson review, slower language practice, and temporary tempo versions. For music production requiring exact beats, locked pitch, or high-quality stretching, use an audio workstation with algorithm and tempo-grid controls.

How to use it

  1. Upload and note duration

    Confirm completeness and choose samples containing both fast and slow passages.

  2. Set a speed multiplier

    Begin with a modest change close to 1.0.

  3. Listen and export

    Check speech clarity, musical transients, and final duration before saving.

Supported range and limits

Range
Typically 0.5x to 2x; both slowing down and speeding up change the total duration
Pitch handling
Time-stretched without pitch shift, so speech still sounds natural rather than chipmunked
Extreme rates
Past roughly 2x or below 0.5x the time-stretching algorithm tends to add a metallic, echoey quality
Output
MP3, re-encoded after the change, so one lossy generation is added
Duration maths
New duration = original ÷ rate, so 1.5x turns 60 minutes into 40
Where it runs
FFmpeg compiled to WebAssembly in your browser; the file is never uploaded

When you would use it

  • Accelerating study audio

    Create a more compact review version of a slow lesson or meeting.

  • Slowing a pronunciation clip

    Reduce the speed of language or instrument demonstrations to hear detail.

  • Getting through a long recording faster

    1.5x turns an hour-long lecture into forty minutes, and exporting it keeps that speed in any player.

What to know before you start

  • Speed changes total duration, and subtitles or timecodes are not synchronized automatically.
  • Extreme rates reduce quality, so inspect multiple sections instead of only the opening.
  • Without pitch preservation, faster speed raises pitch and slower speed lowers it.

Related concepts

playback rate
The speed multiplier of output time relative to original playback.
time stretching
Changing audio duration while attempting to preserve pitch.

Frequently asked questions

Does changing speed also change the pitch?
Speeding up or slowing down changes the duration; the tool focuses on speed, so listen back after export to check the pitch result.
Does changing speed upload my file?
No. Speed processing runs locally in your browser and the audio is never uploaded.
What is this commonly used for?
Often to speed up lectures and podcasts to save time, or slow down teaching and dictation material for easier following.
Does speeding it up raise the pitch?
No. The algorithm time-stretches without shifting pitch, so speech still sounds natural rather than producing the old fast-forward chipmunk effect.
Why does an extreme rate sound metallic?
Time-stretching rearranges audio segments in the time domain. The more extreme the rate, the harder those joins are to hide, and they surface as a metallic or faintly echoey quality. Stay between 0.5x and 2x.
Does changing speed change the file size?
Yes. The duration changes, so at the same bitrate the size changes with it. A 1.5x export is roughly two-thirds the original.

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