Change audio speed
Faster or slower sound, at the same pitch.
Drop files here
or click to choose from your deviceAccepted: MP3, M4A, AAC, WAV, OGG, OGA, OPUS, FLAC, WEBA
Up to 3 files per runUp to 150 MB per file5 runs per dayRemove limits with Pro✓ Works offline
Your files stay on your device
This tool runs entirely in your browser. Nothing is uploaded, nothing is stored, and you can even turn off your internet connection before you start.
Example
Example: a 58½-minute podcast episode at 1.5× to fit a 40-minute commute
A podcast episode, episode-112.mp3, runs 58:30, and the train ride to work is 40 minutes. Settings: Speed 1.5×, Pitch Keep the pitch, Save as MP3 — plays everywhere, Bit rate 64 kbps — speech, smallest file.
- The new length is the old one divided by the speed: 58:30 ÷ 1.5 = 39:00, so the episode ends a minute before the train arrives.
- With the pitch kept, the hosts sound like themselves, only quicker; with Change it with the speed they would come out higher, like a tape played fast.
- At 64 kbps the MP3 is about 18.7 MB (64 kbps × 2,340 seconds ÷ 8). At the default 192 kbps it would be about 56 MB, with no gain for speech.
- Select Change speed and download episode-112-1.5x.mp3: the speed is added to the file name.
| Speed | The 58:30 episode lasts | MP3 at 64 kbps |
|---|---|---|
| 0.75× | 1:18:00 | about 37.4 MB |
| 1.25× | 46:48 | about 22.5 MB |
| 1.5× | 39:00 | about 18.7 MB |
| 1.75× | 33:26 | about 16.0 MB |
| 2× | 29:15 | about 14.0 MB |
| 3× | 19:30 | about 9.4 MB |
episode-112-1.5x.mp3, 39 minutes long, in the hosts’ normal voices. The same page slows music down for practice: a 4:12 song at 0.75× with the pitch kept lasts 5:36 and stays in its key, so you can play along at the same tuning.
How it works
- Drop one or more audio files onto the box: MP3, M4A, WAV, OGG, FLAC and others.
- Choose the speed: above 1 is faster and shorter, below 1 slower and longer.
- Keep the pitch for speech and for practising music; choose to change it for a sped-up or slowed-down effect.
- Select Change speed and download the result.
Frequently asked questions
- Does the voice sound higher when it is faster?
- Not unless you want it to. Keep pitch stretches the sound in time only (WSOLA, which pieces together short overlapping slices of the recording at the new pace), so voices keep their pitch and stay understandable. Change pitch plays it like a tape at another speed: faster and higher, or slower and lower.
- How fast can speech go and still be followed?
- Most people follow speech comfortably at 1.5× and with effort at 2×. Beyond that the slices the stretching is made of start to be heard. For music practice, 0.75× keeps the notes and the key while giving the fingers time.
- Does it take long?
- A song takes seconds. An hour-long recording takes a minute or two on an ordinary computer, most of it spent writing the MP3; saving as M4A or WAV is quicker.
- How long will my file be at 1.5× or 2×?
- The length divided by the speed. An hour-long recording lasts 40 minutes at 1.5× and 30 minutes at 2×; a 58:30 episode lasts 39:00 at 1.5× and 29:15 at 2×. Slowing down works the same way: at 0.75× a 4:12 song lasts 5:36.
- Which format and bit rate should I save as?
- For speech, MP3 at 64 kbps is plenty and keeps the file small: about 29 MB for an hour. For music, 192 kbps MP3 or M4A, which is smaller at the same quality. WAV loses nothing but is large, about 10 MB a minute for CD-quality stereo. Same as the original keeps MP3, M4A and WAV as they were and turns OGG and FLAC into MP3.
- Is my file uploaded, and what are the free limits?
- Nothing is uploaded. The free plan allows 3 files of up to 150 MB per run and 5 runs a day. Pro removes these limits.