How to Change the Key of a Song (Without Changing the Tempo)

To change the key of a song without changing its tempo, find its current key, count the semitones to the key you want, and apply that shift with a pitch shifter that time-stretches — not a speed change. Moving up or down two or three semitones usually sounds natural; beyond about four or five, voices and acoustic instruments start to sound noticeably processed.

SoundGen's free pitch shifter does this in your browser, and the key and BPM finder tells you what key you're starting from.

Step 1: Find the original key

You can't count the distance until you know where you are. Run the song through a key finder, or play along on an instrument until the root note "feels like home". Note whether it's major or minor; transposing keeps the quality, so a song in A minor moved up two semitones is in B minor.

Step 2: Count the semitones

A semitone is one step on a piano keyboard, including the black keys. Twelve semitones make an octave:

C → C♯ → D → D♯ → E → F → F♯ → G → G♯ → A → A♯ → B → C

Some examples:

• G major to A major: +2
• E minor to C minor: −4
• C major to F major: +5, or −7

That last one matters. Moving up five and moving down seven land in the same key, an octave apart. Always pick the smaller shift. Up five sounds cleaner than down seven, and a 12-semitone shift is the same key an octave away — rarely what you want.

Quick reference for singers and guitarists

• Song too high to sing? Try −2 or −3 first, then adjust by ear.
• Guitarists: a capo raises the key by one semitone per fret, so +2 is a capo at the second fret with the original chord shapes; −2 is the original shapes with the guitar tuned down a whole step.

Step 3: Shift the pitch, not the speed

There are two ways to make audio higher or lower, and only one keeps the tempo.

Resampling (varispeed)

Playing a recording faster raises its pitch and shortens it; slowing it lowers both. It's how tape and turntables work. Every semitone is a speed change of about 6% (the ratio is the twelfth root of two, ≈1.0595), so +2 semitones is about 12% faster. Varispeed sounds very natural — nothing is synthesised — but the tempo changes with the key.

Pitch shifting with time-stretching

A pitch shifter changes pitch while keeping the duration, by analysing the audio in short overlapping slices and resynthesising them. Phase-vocoder designs work in the frequency domain; others splice and overlap waveform segments. Either way, the tempo stays put and only the key moves. That's what you want for transposing a song.

Formants: why voices go chipmunk

A voice has two separate things going on: the pitch of the note and the formants, resonances set by the shape of the singer's throat and mouth. Formants are why an "ah" sounds like "ah" whatever note it's sung on, and why you can tell an adult from a child.

A plain transposition moves the formants along with the pitch. Shift a voice up five semitones and it sounds like a smaller person ("chipmunk"); shift it down and it sounds huge and muffled. Formant-preserving shifters keep the resonances in place and move only the pitch, which is far more convincing on vocals. On instruments formants matter less, but body resonance on acoustic guitar and piano gets the same effect.

How far can you shift before it sounds bad?

As a rule of thumb:

• ±1 to 3 semitones: usually clean on most material.
• ±4 to 6: audible on vocals and sustained acoustic sounds; fine on synths and many electronic parts.
• Beyond ±7: treat as a sound-design effect.

Typical artifacts are smeared transients (drums lose their snap), phasiness or a slightly hollow tone on sustained chords, and the formant shift on voices. Dense full mixes with drums tend to hide less than you'd hope; separating the song into stems first and shifting only the pitched parts (leaving drums alone) often sounds better.

Doing it in SoundGen

• One file, quickly: the free pitch shifter.
• In a project: in the studio, set a clip's pitch shift in semitones. The clip keeps its length and stays on the grid. Clip pitch shift is a plain transposition — formants move with the pitch — so keep vocal shifts small. For live use there's also a Pitch Shift effect you can put on a track.
• Stems first: run Stem Separation, shift the vocals, bass and other stems, and leave the drums unshifted.

FAQ

Will changing the key change the tempo? Not with a pitch shifter, which time-stretches to keep the length. Only varispeed (speeding up or slowing down) changes both.

How many semitones is a whole step? Two. A half step is one semitone.

Why does my vocal sound like a chipmunk after shifting up? The formants moved up with the pitch. Use a smaller shift or a formant-preserving shifter.

Is it better to shift up or down? Whichever reaches the target key in fewer semitones. The smaller the shift, the fewer the artifacts.

Can I change the key of just the vocal? Only if you have the vocal on its own. Separate the song into stems, shift the vocal stem, and remix it with the others — but the vocal will then be in a different key from the band, so this is normally for harmonies and sound design.