Does the sound change as I move the slider?

No. You set the key and the speed, and pressing "Convert" rebuilds the whole track from there. The browser's own playback controls cannot separate pitch from speed, which is why the conversion is a distinct step. A three-minute track takes a few seconds to a few tens of seconds.

How far can I move it?

Up to ±6 semitones of key, plus cents, and 50–150% of tempo. In practice ±3 to 4 semitones and 70–130% is the range that stays clean; beyond that, drums and cymbals start to smear.

Is this the same as "key +2" on a karaoke machine?

The same idea. One step of karaoke key is one semitone, so setting the semitone slider to the same number moves a backing track to your key.

How do I find the key that suits me?

If the top of the chorus is a strain, go down; if it sits low and you have breath to spare, go up. Between typical male and female ranges the gap is 4 to 5 semitones. Try ±2 first, then move a semitone at a time — the character of the song shifts as you go, so pick the best-sounding point inside the range you can actually sing.

Can I retune an A=442 or A=432 recording to 440?

Yes, with the cents control. A=442 is about +8 cents, so it needs −8; A=432 is about −32 cents, so it needs +32. The audio analyser reports a track's tuning offset in cents — put in that figure with the sign flipped.

Is my audio uploaded?

No. Reading, converting and exporting all happen inside your browser, and the audio is never sent anywhere.

A semitone is one twelfth of an octave, the smallest step in ordinary tuning. "Key +2" on a karaoke machine is two semitones — a whole tone. Note that neighbouring letters are not all a tone apart: C to D is two semitones, E to F is one.

One hundredth of a semitone. A recording at A=442 Hz sits about 8 cents above A=440; A=432 is about 32 cents below. Offsets that small cannot be written in semitones, which is why there is a separate control for them.

Playback speed with the original at 100%. At 80% the track is 1.25× longer, and a 120 BPM song plays at 96 BPM. For picking a fast line out by ear, somewhere around 70–80% is usually where the notes separate.

Male ↔ female range

Moving a song between typical male and female ranges is usually 4 to 5 semitones — a major third or a fourth. Start at −5 or +5, then close in a semitone at a time on whether the highest note of the chorus is reachable.

Why slowing it down does not lower the pitch

A tape drops in pitch because it stretches the waveform itself. This tool instead breaks the sound into short slices, describes each as a set of frequencies, and lays them back down at the original pitch — a phase vocoder. That is what makes speed and pitch two independent numbers.

What that model is bad at is anything that starts instantly: drum hits and cymbals. The further you move, the softer the attacks get and the more the cymbals take on a brushed, grainy quality. Voices and guitars survive far larger moves.

Pitch without tempo · tempo without pitch

Change the key, or the speed

Key (semitones)Tempo (speed)

Want the current key and BPM first? Try the analyser →

Input

Drag & drop the track you want to move

or click to choose

MP3, WAV, M4A, AAC, FLAC, OGG, Opus, AIFF and more — plus the audio of MP4, MOV, WebM and other video

Result

Nothing here yet

Slow a track down without the pitch dropping. Move it to your key without it slowing down. For learning parts by ear, singing along and sampling — all inside the browser.

Related purposes

Change the key of a backing track Slow a track down to work it out by ear Speed a track up Retune an A=442 recording to A=440

What this tool does

Speed and key, separately: Slowing a track down normally drags the pitch down with it. This tool treats stretching and pitch as two different things, so at 70% the key has not moved — and the reverse works too: same speed, key up a semitone.
Semitones and cents: Semitone steps, the same units a karaoke machine uses, plus a cent-level fine tune. A recording made at A=442 Hz is off by an amount no semitone can express; that is what the cents control is for.
Compare before and after: Hold "hear the original" to switch to the unconverted audio at the same point in the track.

How to use

Choose a track
Drag and drop the track whose key or speed you want to change, or click to choose it.
Set the key and the speed
Key in semitones, a fine trim in cents, and tempo as a percentage all move independently. Nothing about the sound changes while you drag — the sliders only set the numbers.
Convert, listen, export
Pressing convert rebuilds the whole track. Then play it back, hold "hear the original" to compare against the source, and save as WAV or MP3.

Terms and rules of thumb

Semitone / key: A semitone is one twelfth of an octave, the smallest step in ordinary tuning. "Key +2" on a karaoke machine is two semitones — a whole tone. Note that neighbouring letters are not all a tone apart: C to D is two semitones, E to F is one.
Cents: One hundredth of a semitone. A recording at A=442 Hz sits about 8 cents above A=440; A=432 is about 32 cents below. Offsets that small cannot be written in semitones, which is why there is a separate control for them.
Tempo (%): Playback speed with the original at 100%. At 80% the track is 1.25× longer, and a 120 BPM song plays at 96 BPM. For picking a fast line out by ear, somewhere around 70–80% is usually where the notes separate.
Male ↔ female range: Moving a song between typical male and female ranges is usually 4 to 5 semitones — a major third or a fourth. Start at −5 or +5, then close in a semitone at a time on whether the highest note of the chorus is reachable.
Why slowing it down does not lower the pitch: A tape drops in pitch because it stretches the waveform itself. This tool instead breaks the sound into short slices, describes each as a set of frequencies, and lays them back down at the original pitch — a phase vocoder. That is what makes speed and pitch two independent numbers.
Smearing (artefacts): What that model is bad at is anything that starts instantly: drum hits and cymbals. The further you move, the softer the attacks get and the more the cymbals take on a brushed, grainy quality. Voices and guitars survive far larger moves.

Frequently asked questions

Does the sound change as I move the slider?: No. You set the key and the speed, and pressing "Convert" rebuilds the whole track from there. The browser's own playback controls cannot separate pitch from speed, which is why the conversion is a distinct step. A three-minute track takes a few seconds to a few tens of seconds.
How far can I move it?: Up to ±6 semitones of key, plus cents, and 50–150% of tempo. In practice ±3 to 4 semitones and 70–130% is the range that stays clean; beyond that, drums and cymbals start to smear.
Is this the same as "key +2" on a karaoke machine?: The same idea. One step of karaoke key is one semitone, so setting the semitone slider to the same number moves a backing track to your key.
How do I find the key that suits me?: If the top of the chorus is a strain, go down; if it sits low and you have breath to spare, go up. Between typical male and female ranges the gap is 4 to 5 semitones. Try ±2 first, then move a semitone at a time — the character of the song shifts as you go, so pick the best-sounding point inside the range you can actually sing.
Can I retune an A=442 or A=432 recording to 440?: Yes, with the cents control. A=442 is about +8 cents, so it needs −8; A=432 is about −32 cents, so it needs +32. The audio analyser reports a track's tuning offset in cents — put in that figure with the sign flipped.
Is my audio uploaded?: No. Reading, converting and exporting all happen inside your browser, and the audio is never sent anywhere.