About Audio Speed Changer
Changing playback speed is useful for more than entertainment: a recorded lecture becomes a manageable commute listen at 1.5x, a music passage is easier to learn at 0.75x, and a slow voice note can be tightened without cutting words. The catch is that naive speed changes also shift pitch, turning voices into chipmunks.
This tool uses FFmpeg's atempo filter, which time-stretches the audio and preserves pitch, and chains it when the requested speed is outside a single filter's range. Choose anything from 0.25x to 4x, see the estimated new length before you start, and export the result as MP3, WAV or M4A. The uploaded file is deleted from the server after your download.
What this tool does
0.25x to 4x speeds
Slow a recording to a quarter speed or speed it up four times over. The default 1.5x is a comfortable pace for most spoken-word material.
Pitch stays natural
atempo changes tempo by stretching the waveform, so a faster voice still sounds like the same person rather than a higher-pitched version.
Length estimate first
The workspace shows the expected duration, original length divided by the speed, so you know whether a 1.5x cut fits your commute before converting.
Chained filter for extremes
A single atempo pass handles 0.5x to 2x; 4x becomes 2x twice and 0.25x becomes 0.5x twice, which keeps the filter within its supported range.
Three output formats
Download an MP3 for players and podcast apps, a WAV for editing, or an M4A for efficient storage on Apple devices, with a bitrate option for lossy formats.
Automatic cleanup
The upload and the converted file are written to a temporary folder and deleted automatically once the download finishes.
How to use Audio Speed Changer
- 01
Add the audio file
Drop an MP3, WAV, M4A or another supported audio file into the workspace. Uploads up to 100 MB are accepted.
- 02
Choose the playback speed
Set a multiplier between 0.25x and 4x. Values above 1x shorten the file; values below 1x stretch it out.
- 03
Check the estimated length
The workspace shows how long the result will be after the speed change, calculated from the source duration divided by the speed.
- 04
Pick a format and convert
Choose MP3, WAV or M4A, then click Change speed and wait for the server-side conversion.
- 05
Listen and download
Preview the result in the player and download it. If the speed is not right, start over and try a different multiplier.
Supported formats and limits
- Input
- MP3WAVM4AAACFLACOGGOPUSWMA
- Output
- MP3 / WAV / M4A
- Processing
- Server-side FFmpeg job in a temporary directory, deleted after download.
- Maximum size
- Up to 100 MB
- Requirements
- Chrome, Edge, Firefox or Safari · Server-side FFmpeg conversion
Limitations worth knowing
- Pitch follows the natural time-stretch only: there is no tape-effect option that shifts pitch with speed.
- Extreme speeds such as 0.25x and 4x can introduce audible artefacts, especially with percussion and complex music.
- MP3 and M4A outputs are lossy re-encodes; WAV avoids the extra codec but is much larger.
- One file per job, 100 MB maximum, three-minute processing limit.
Privacy and file handling
The audio file is uploaded to a temporary directory on our server, processed with FFmpeg's atempo filter, and streamed back as a download. The upload and the speed-changed copy are deleted automatically when the download finishes; nothing is stored permanently or shared.
Read the full privacy policy