Change Audio Speed

How it works

1. Choose an audio file.
2. Pick a speed preset or type a value, and choose whether pitch is preserved.
3. Preview the result.
4. Export and download.

Two ways to change speed

Tempo (keep pitch) stretches or squeezes time without changing the pitch, so a voice at 1.5x still sounds like the same person. This uses a phase-vocoder time-stretch engine that runs in your browser.

Speed (pitch changes) simply plays the samples faster or slower, like a record or tape. Everything moves together: at 2x the audio is an octave higher, at 0.5x an octave lower. It is exact and fast, and it is what gives the "chipmunk" and "slowed down" sounds.

Quality and limits

Time-stretching works best between 0.5x and 2x. Beyond that, and on sharp drums or dense mixes, you may hear smearing or a slight "phasey" quality; this is inherent to the method. Speech and solo instruments hold up best.

The length of the result is exact: a 3 minute file at 1.5x becomes 2 minutes. The tool shows the new length before you export. You can choose any speed between 0.25x and 4x.

Working on part of a file

Select a range on the waveform and turn on "Process only the selected part" to change just that part; the output then contains only the selection. The preview plays 10 seconds from the playhead or the start of the selection, so you can hear a setting before processing the whole file.

Questions