Tempo and speed changerBeta
Tempo changer
Change the speed of any song and keep it in tune. Slow it down to learn a part, speed it up for a workout. We show the BPM before and after.
- Free
- No sign-up
- Runs in your browser
- Nothing is uploaded
Loading the tool
How it works
- 01
Drop a track
Any song up to 8 minutes: MP3, WAV, FLAC, M4A, OGG or the sound of a video. It never leaves your device.
- 02
Set the speed
Drag from 50 to 150 percent. We measure the tempo and show the new BPM, so 120 at 90 percent reads 108 BPM.
- 03
Save the result
Listen against the original, then download a WAV at the new tempo, in the same key.
Practise at your own speed
Learning a solo at full tempo is how bad habits start. Teachers tell students to play it slowly first, then a little faster, and to speed up only when it is clean. Set the song to 70 percent, play along until it is easy, then try 80, then 90.
Because the pitch stays the same, your instrument stays in tune with the recording at every speed. A guitar part at 75 percent is still in E, just slower, so you can hear every note of a fast run and copy the fingering.
Dancers rehearsing choreography, language learners following a song's words and transcribers writing out a part all use the same trick. Slow it down, get it right, bring it back up.
BPM, percent and what the numbers mean
The speed is a percentage of the original. At 100 percent nothing changes. At 50 percent the song lasts twice as long. At 125 percent a three minute song lasts two minutes and twenty four seconds.
We also measure the tempo of the track in beats per minute and multiply it by the speed, so you can aim for a number. A DJ who needs a 124 BPM track at 128 sets about 103 percent. A runner who wants 170 steps a minute can match a song to that cadence.
Tempo detection works best on music with a steady beat. Rubato piano or a live band that drifts may not give a single number, and in that case we only show the percentage.
How the speed changes without the pitch
If you simply play a recording faster, every frequency goes up with it, which is why old tape sped up sounds like cartoon voices. A tempo changer has to separate the two: it cuts the sound into short overlapping windows, spaces them further apart or closer together, and rebuilds a smooth signal from them.
We use signalsmith-stretch, an open source library built for exactly this, with long windows that keep chords and bass solid. Moderate changes, from about 80 to 125 percent, sound very close to the original. Extreme settings can smear sharp drum hits a little, as with any time stretching.
If you also want a new key, the semitone slider moves the pitch at the same time, in one pass, so the sound is processed only once.
What you get
- Speed from 50 to 150 percent, in steps of one percent
- Pitch stays in tune at any speed
- The song's BPM measured, and the new BPM shown as you drag
- Optional key change in semitones at the same time
- Live preview and an A/B with the original
- WAV download at the original loudness, never clipping
- Free, no sign-up, the song stays on your device
Slowing down a song: the options
| OBRA tempo changer | Playback speed in a player | Typical upload tools | |
|---|---|---|---|
| Pitch | Stays in tune | Stays in tune in most modern players | Usually stays in tune |
| BPM shown | Before and after | No | Rarely |
| A file to keep | Yes, a WAV | No, only while it plays | Yes, often MP3 |
| Privacy | Processed in your browser | Local | Uploaded to a server |
| Range | 50 to 150 percent, in 1 percent steps | A few fixed steps | Varies |
Player speed buttons are great for a quick listen. When you need the slowed version on your phone, in a DAW or on a USB stick for a class, a file is what you want.
Frequently asked questions
Can I slow down a song without changing the pitch?
Yes, that is what this tool does. The pitch stays the same at every speed from 50 to 150 percent.
How do I speed up a song to an exact BPM?
Drop the song and we show its BPM. Move the speed until the new BPM reads the number you want. The percentage and the BPM update together.
What is the best speed for practising?
Start where you can play every note cleanly, often 60 to 75 percent, and raise it in small steps. The one percent steps make that easy.
Does slowing a song down lower its quality?
Moderate changes sound very close to the original. Very slow settings, under about 60 percent, can make drum hits a little softer, as any time stretching does.
Can I change the key as well?
Yes. The semitone slider shifts the pitch while you change the speed, and both are rendered together.
Which formats can I use?
MP3, WAV, FLAC, M4A, AAC, OGG and video files your browser can play, up to 8 minutes. The result is a WAV.
Is it really free?
Yes. No sign-up, no watermark, and the song is processed in your browser, never uploaded.
More free music tools
- BetaPitch shifterChange the key of a song by semitones and keep its tempo, with the new key shown.
- BetaBPM finderFind the BPM of any song, with half and double time and a click to check it.
- BetaSlowed and reverb makerTurn a song into a slowed and reverb version: slower, lower and wrapped in a long dark reverb.
- BetaNightcore makerMake a nightcore or sped up version of a song: faster, higher, brighter.
- BetaVocal removerRemove the vocals from a song and keep the instrumental.
Finish the track
Learn more, or get a person on it
Read the mastering guides, comparisons and data, or send your tracks to an engineer with OBRA ULTRA.
Happy with the result?
Master it on OBRA Audio Mastering: three masters measured in LUFS, free to listen, in your browser.