How to change the speed of audio
- Add a file. Drop in a song, podcast, lecture, voice memo or audiobook.
- Set the speed. Drag the slider or tap a preset: values below 1× slow the audio down, values above 1× speed it up. The new length appears below the slider.
- Choose pitch behaviour. Leave Keep original pitch on for natural-sounding speech and music, or turn it off for a tape-style effect.
- Download. Press Change speed, preview, and save as MP3 or WAV.
Keep pitch or change pitch?
With pitch kept (time-stretching), the tool uses Signalsmith Stretch, a modern polyphonic time-stretching engine. It works in the frequency domain, stretching every note and chord cleanly, so the tempo changes while voices and instruments keep their natural tone. If your browser can't run it, a fast WSOLA (waveform-similarity overlap-add) fallback is used instead. This is what you want for:
- listening to podcasts, lectures and audiobooks faster (1.25×–2×),
- slowing down a guitar solo or a fast passage to learn it (0.5×–0.75×),
- slowing speech for language learning and transcription,
- fitting a voice-over or music bed to an exact length.
With pitch change (resampling), the audio is simply played faster or slower, like changing the speed of a record player. Faster sounds higher (the "chipmunk" effect), and slower sounds deeper. It's perfect for "sped up" and "slowed + reverb" edits, and it has no stretching artefacts because nothing is cut up.
Tips
- Speech stays clear up to about 1.75× with pitch kept. Beyond that it becomes harder to follow.
- Small changes (0.9×–1.1×) are almost impossible to notice in music, which makes them handy for matching tempos in a DJ set.
- Extreme slowdowns of dense music can sound slightly "phasey". That's normal for any time-stretch.
- To change the length of only part of a file, cut it first with the Audio Cutter.
- Want a different key instead of a different speed? Use the Audio Scale Changer.
Frequently asked questions
Can I speed up audio without changing the pitch?
Yes. Keep original pitch is on by default, so the audio gets faster or slower while voices keep their normal tone.
How do I make a slowed or sped-up version of a song?
Turn off Keep original pitch, then choose around 0.8× for a slowed version or 1.25× for a sped-up version.
What speed range is supported?
From half speed (0.5×) to double speed (2×), in 0.05 steps.
Is it free and private?
Yes. The speed changer is free and processes audio in your browser, so nothing is uploaded.