// effects · tool 09
Audio Speed Changer
Slow a track down to learn it, or speed a lecture up to save time — 0.25× to 4×, with instant preview.
Drop your audio file here
MP3, WAV, M4A, OGG, FLAC and more — or click to browse
[ drop works anywhere on this page ]
Change audio speed without installing anything
This tool decodes your file with the Web Audio API and re-renders it at the chosen rate using an OfflineAudioContext — entirely on your device. Slowing to 0.5× doubles the duration; speeding to 2× halves it. The new length is shown live as you move the slider.
Pitch: preview vs. export
While previewing, your browser applies built-in time-stretching, so voices keep their natural pitch. The downloaded file is rendered with varispeed resampling, which shifts pitch with speed — the classic turntable effect. For slowed + reverb edits, practice loops and lecture skimming, that's usually exactly what you want. If you need pitch to stay put, run the result through our Pitch Shifter to correct it.
Popular uses
- Slowing guitar solos or piano pieces to practice along.
- Speeding lectures, meetings and voice memos to 1.5–2×.
- Creating slowed-down or nightcore-style versions of songs.
FAQ
Does changing speed change the pitch?
The live preview keeps the original pitch. The exported file uses varispeed, so pitch shifts with speed — slower sounds deeper, faster sounds higher.
What speeds are supported?
Anything from 0.25× to 4×, in 5% steps, with one-click presets for common values.
Will a sped-up file be smaller?
Yes — at 2× the file is half the duration, so roughly half the size at the same bitrate.