Music Speed Changer
Drop in a song or any audio file, set the speed as a percentage, listen, and export a WAV with the pitch unchanged. It runs in your browser, handles files up to 150 MB and 15 minutes, and nothing is sent anywhere.
Use audio you made or have permission to use. Nothing is sent anywhere, so we never hear or keep it.
Speed set. Melodious can turn the finished track into a music video — See the music video maker
Eight worked examples
The first six cases run the tool's own engine on a generated 440 Hz tone, two seconds long, and count the cycles in what comes out. The last two show how the size limit applies to a longer track. Music is more complicated than a single tone, so these show that the arithmetic is right, not how a full mix will sound.
25% faster, 125%
- Speed: 125% of the original
- Length: 0:02.000 in, 0:01.600 out
- Pitch of the 440 Hz tone, measured: 439.7 Hz
Twice as fast, 200%
- Speed: 200% of the original
- Length: 0:02.000 in, 0:01.000 out
- Pitch of the 440 Hz tone, measured: 440.0 Hz
20% slower, 80%
- Speed: 80% of the original
- Length: 0:02.000 in, 0:02.500 out
- Pitch of the 440 Hz tone, measured: 440.2 Hz
Half speed, 50%
- Speed: 50% of the original
- Length: 0:02.000 in, 0:04.000 out
- Pitch of the 440 Hz tone, measured: 439.9 Hz
100% is refused, because it would change nothing
- Refused: 100% is the original speed. Choose a number other than 100.
Slower than 50% is refused
- Refused: This tool changes speed between 50% and 200%.
A six-minute track at 90%
- Six-minute stereo track at 90%: 6:40.000, 67.3 MB
The same track at half speed is over the size limit
- Refused: That WAV would be 121.1 MB. The limit is 100.0 MB, because the file is built in your browser's memory. Choose a faster setting or a shorter file.
Slowing a file down makes it longer, so the output can be over the size limit even when the input was not. Duration is the number of frames divided by the sample rate, which is how a player reads a WAV.
How to change the speed of an audio file
Drop an audio file onto the box, or choose one. The page decodes it and draws its waveform. Enter the speed as a percentage of the original, or move the slider: 100 is unchanged, anything above is faster and shorter, anything below is slower and longer. The readout shows the new length straight away.
Press Play the result to hear the first thirty seconds processed exactly as the export will be. When it sounds right, press the export button. The work takes a few seconds, with a progress figure and a Cancel button while it runs, and the file downloads when it is done.
Speed without the pitch moving
Slowing a record slows the sound and lowers it; speeding it up raises it. That is because the speed and the pitch are one thing: how fast the wave repeats. This tool separates them. It cuts the audio into overlapping grains of about 46 milliseconds and lays them back at a different spacing, so the sound takes more or less time while each grain keeps the pitch it had.
The grains are not placed blindly. Each is nudged by a few milliseconds to the position where its waveform best continues the grain before, which keeps a sustained note from warbling. The method is a good one and has weak spots: long sustained tones come out clean, while sharp drum hits can lose a little of their edge when the change is large.
Slowing a passage to practise it
For learning a part by ear, slow it to between 50% and 80% and keep the pitch right, so what you hear is what to play. Cut the passage out first with the audio cutter, so that you work on twelve seconds and not three minutes, and use the audio loop maker to repeat it.
Speeding up is the same tool in the other direction. A voice memo, a lecture or an interview at 150% is still natural and takes two thirds of the time to hear. Beyond 150% speech starts to lose its consonants, and the readout will say when a change is large enough to listen for.
Limits, stated up front
The speed can be set from 50% to 200%. The tool opens files up to 150 MB and 15 minutes and refuses to write a WAV over 100 MB. Because a slower file is longer, the size limit is checked against the result: a track that opens fine can be refused at 50% because the answer would be too big, and the message says so and gives the size.
It handles mono and stereo, keeps the first two channels of anything larger, and writes a 16-bit WAV at the rate your browser decoded the file at. It does not change the pitch, so it is not the effect that raises or lowers the pitch along with the speed. It does not detect the tempo of a track in beats per minute. Phones have less memory and are slower than computers.
Working out the percentage you need
To land on an exact tempo, find the current one first. The BPM finder reads it from a file and the tap tempo page lets you tap it out. If a track is at 100 beats per minute and you want 120, the speed is 120 divided by 100, which is 120%. If it is at 128 and you want 110, the speed is about 86%.
To move the pitch as well, the pitch changer does that, and the volume booster sets the level afterwards.
From a track at the right speed to a finished video
A track at the right tempo is ready to go under a picture. For the wider route, the guide to making a music video for your song covers it end to end.
When the finished track should have scenes, a character and a story, the AI music video generator storyboards it and renders it to your audio. It is paid, from $19/month, and you see the cost before anything renders. The WAV you make here stays on your device unless you upload it yourself.
Frequently asked questions
How do I speed up or slow down audio without changing the pitch?
Drop the file onto the box, enter a speed as a percentage of the original (125 is a quarter faster, 80 is a fifth slower), listen to the preview and export. The pitch stays where it was, so a voice does not turn into a chipmunk when you speed it up or a monster when you slow it down.
What is the difference between changing speed and changing pitch?
On a record player the two move together: faster is higher, slower is lower. A digital tool can pull them apart. This page changes how long the sound takes and leaves its pitch alone. The pitch changer on this site does the reverse and leaves the length alone. Use both, one after the other, if you want both to move.
How slow or fast can I go?
From 50% to 200% of the original speed. Within about a third either way, a full mix stays natural. At the extremes a mix gets smeared, and speech gets a slight watery quality. Half speed is long enough to hear a fast passage clearly, and double is fast enough to skim a lecture.
Can I use it to learn a song or a solo by ear?
Yes, and it is one of the best uses. Slow the passage to 60% or 70% and the notes are still at the right pitch, so you can match them on your instrument. Cut the section first with the audio cutter so you are not slowing three minutes to study twelve seconds, then loop it in whatever player you like.
Will the file get longer when I slow it down?
Yes, by exactly the factor you chose. At 50% a two-minute file becomes four minutes. The readout above the buttons shows the new length and the file size before you export, and the size limit applies to the result, not to the file you started with, so a long track at a slow setting can be refused when the original was not.
Is it as good as the speed control in a podcast app?
A podcast app does the same trick as it plays, and does it for speech, which is the easy case. This tool saves the result as a file, which is useful when you want to keep it, edit it or put it under a video. On speech, up to about 150%, it should sound natural; on dense music, small changes sound better than big ones.
Does changing the speed happen live, and how long does it take?
It is not real time. The preview and the export work through the file as fast as your device can, and a track of a few minutes usually takes a few seconds. A progress figure and a Cancel button show while it works. The preview covers the first thirty seconds so you hear the effect quickly, and a phone is slower than a computer.
How long a file can I open, and what does it write?
It opens files up to 150 MB and 15 minutes, and writes an uncompressed 16-bit WAV up to 100 MB, about 9.9 minutes of stereo at 44,100 Hz. A WAV is much larger than an MP3 of the same sound, and it adds no further loss. Past a limit the tool refuses and says what would fit.
Does the speed changer upload my audio?
No. The file is read by your browser, processed by code running in your browser and saved back to your device. There is no upload step, no account and no engine to download, and the code that changes the speed contains no network call. Closing the tab clears it. Your browser's network tab will show no request carrying your audio.
Can I change the speed of audio that is not mine?
Only with permission. Use audio you made or have permission to use. A sped-up or slowed copy of a commercial recording is still a copy, and posting it can infringe the copyright even though it sounds different. The tool cannot tell whose audio a file holds, so the check is yours.
At the speed you wanted. The video is next
Attach the track and describe the look. An AI director storyboards it scene by scene and renders it to your audio. Plans from $19/month, and you see the cost before anything renders.
Start your videoMore tools: Pitch changer · BPM finder · Tap tempo · Audio cutter · Audio loop maker · Volume booster