Pitch Changer (Key Transposer)
Move a song into the singer’s key and hear it change while it plays.
Try before you buy.
- Free preview: the first half of the result (up to 30 seconds) at the quality you chose, with a short MySmartCoPilot chime every 10 seconds.
- Locked until you unlock it: download and share.
- Unlock: Pro pass, ₹179 for 30 days or ₹79 for 1 week, a one-time payment that never renews. Unlock: Pro pass, $5.99 for 30 days or $2.99 for 1 week, a one-time payment that never renews.
Ways to unlock shows how to get the full result.
Printing this result is locked in the free preview.
Pitch
100 cents are one semitone. The tempo never changes.
Listen
30 seconds of the file loop while you listen; the loudest part is picked first.
Sing or play along with the Shifted side to find the key that suits you, then make the file.
Result
Locked in the free preview. Opens the ways to unlock this result.
Locked in the free preview. Batch runs unlock with a pass.
Locked in the free preview. Query results unlock with a pass.
About the Pitch Changer (Key Transposer)
Change the key of a song without changing its speed: shift it up or down by up to 12 semitones, plus a fine tuning in cents, to put a song in a singer’s range, to play along with a backing track on an instrument tuned another way, or to move a recording tuned to A = 432 Hz to A = 440 Hz and back. The page estimates the song’s key and its tuning, so you can pick the key to move it to instead of counting semitones.
Hear it while you change it. Thirty seconds of the song loop at the new pitch while you move the sliders, next to the original, and the file is then made with the same engine, Signalsmith Stretch. A formant correction keeps voices sounding like themselves when they move up or down. A video keeps its picture.
Everything happens in your browser and nothing is uploaded. The free preview on this page is the first half of the result (up to 30 seconds) with a short MySmartCoPilot chime every 10 seconds; a Pro pass, or unlocking this one result, gives the whole file.
How to use it
- Choose or drop a song, backing track or video (MP3, M4A, WAV, FLAC, OGG, MP4, MOV, MKV, WebM…). The page estimates its key and tuning.
- Move Semitones (or press −1 and +1), or under Transpose to another key check the key the song is in and pick the key to Move it to: the shortest shift there is chosen. Use Fine tune for cents, or Retune between reference pitches, for example from A = 440 Hz to 432 Hz.
- Press Play under Listen and switch between Original and Shifted: the pitch follows the sliders while it plays. Keep Keep voices natural on for songs with singing.
- Choose the format under Save as and press Change the pitch: without a pass you get the free preview to listen to; with a Pro pass, or once this result is unlocked, Download or Share gives the whole file.
Examples
song.mp3 · estimated key G major · Move it to E major (−3) · keep voices natural
song-down-3-semitones.mp3: the same length and tempo, a minor third lower, so the melody sits where the singer is comfortable.
backing.wav · Retune between reference pitches: from A = 440 Hz to A = 432 Hz (−31.77 cents)
backing-minus-32-cents.wav: about a third of a semitone lower, in tune with the instrument.
karaoke.mp4 · +2 semitones · the same kind of file
karaoke-up-2-semitones.mp4 with the picture copied unchanged and the music a whole tone higher.
Semitones, cents and frequencies
In equal temperament every semitone multiplies each frequency by 2^(1/12) ≈ 1.0595, so a shift of n semitones multiplies it by 2^(n/12): +12 semitones doubles every frequency (an octave up), +7 multiplies it by about 1.498 (a perfect fifth) and −3 by about 0.841 (a minor third down). A cent is a hundredth of a semitone, a factor of 2^(1/1200); two tunings are 1200 × log₂(f₂ / f₁) cents apart, so A = 440 Hz to A = 432 Hz is about −31.77 cents (cent). The page shows the factor of every shift next to the sliders.
How the key is estimated
The page listens to the whole song once, places every spectral peak between 65 Hz and 2.1 kHz on the circle of the 12 pitch classes, and measures how far the notes are tuned from A = 440 Hz. It then compares how much of each pitch class sounds with Krumhansl and Kessler’s profiles of all 24 major and minor keys — the Krumhansl–Schmuckler method — and names the key that fits best. A major key and its relative minor (G major and E minor) share their notes, so both are named when they fit almost equally well. It is an estimate: songs that change key, modal music and tracks with few held notes can mislead it, so check it by ear and set the key yourself if needed.
How the pitch is changed
The shift is made by Signalsmith Stretch (MIT licence), a pitch-shifting and time-stretching library that runs as WebAssembly in your browser’s audio engine, with the speed held at 1×. Formant correction keeps the resonances of a voice — what makes it sound like that person — in place while the notes move, so a voice shifted up does not sound like a cartoon. The file is made in 30-second pieces that overlap and are cross-faded, so long recordings do not run out of memory.
In the tests behind this page, steady tones from 220 Hz up came out within about 3 cents of the exact new pitch, and bass notes near 110 Hz within about 6 cents (a cent is a hundredth of a semitone).
Limitations
- Quality is best within about ±5 semitones; larger shifts, of voices especially, start to sound processed.
- The key estimate can be wrong for songs that change key, modal or atonal music and tracks with few held notes; choose the key yourself then.
- The live preview loops 30 seconds; the file always covers the whole recording.
- Up to 2 hours on a computer and 30 minutes on a phone; files with several sound tracks keep only the main one.
- To change the speed instead of the pitch, use the Audio Speed Changer.
Privacy
On this device; its files download once
Everything happens in your browser. What you enter or open here is not uploaded or stored by MySmartCoPilot. The audio engine, the pitch engine (Signalsmith Stretch) and, when your file needs it, the MP3, AAC or FLAC encoder download from MySmartCoPilot the first time you open a file. Your songs are never uploaded.
Frequently asked questions
What do I get without a pass?
Without a pass, Pitch Changer (Key Transposer) shows the first half of the result (up to 30 seconds) at the quality you chose, with a short MySmartCoPilot chime every 10 seconds. Until you unlock it, the result can’t be downloaded or shared. A Pro, Premium or Ultimate pass, a one-time payment that never renews, unlocks the full result. The pricing page lists the passes and their prices.
Does the speed change?
No. Only the pitch moves: the result has the same length and tempo as the original, so it still fits a video or a dance routine made to it.
How do I find the right key for a singer?
Play the Shifted side and sing along, moving one semitone at a time with −1 and +1, until the highest and the lowest notes of the melody are comfortable. If you know the key you want, check the song’s key under Transpose to another key and pick the target key instead.
What is 432 Hz tuning?
Most music is tuned with the A above middle C at 440 Hz. Some recordings and instruments are tuned to A = 432 Hz instead, about 31.8 cents (a third of a semitone) lower. Retune between reference pitches moves a recording from one to the other: 440 to 432 Hz is −31.77 cents. The page also says how the song you open is tuned.
Will a voice sound like a chipmunk?
Not with Keep voices natural on: the formant correction keeps the character of the voice while its notes move, so a few semitones up or down still sound like the same person. Without it, a voice shifted up sounds smaller and one shifted down sounds larger.
Is my song uploaded?
No. The file is read, shifted and written again in your browser, on your own device; nothing about it is sent anywhere.
What does the free preview include?
Without a pass the page shifts the first half of your song, up to 30 seconds, in the format you chose, with a short MySmartCoPilot chime every 10 seconds, and plays it here; for a video, the first half up to 10 seconds with a watermark on the picture. The live Listen player works too, with the chime on the Shifted side. The whole file needs a Pro pass, or an unlock of this one result, which makes it from the file still open on the page.
Open-source components
This page can load these open-source components, each only when a task needs it:
- It uses FFmpeg under the LGPLv2.1 and the LAME MP3 encoder under the LGPL, through libav.js: licence and source code.
- It uses FFmpeg under the LGPLv2.1, through the Mediabunny add-ons: licence and source code.
- It uses the LAME MP3 encoder under the LGPL, through the Mediabunny MP3 add-on: licence and source code.
- It uses Mediabunny under the MPL 2.0: licence and source code.
You may replace them with your own builds. Their licences and the credits of every library the site uses are on the open-source credits page.