Audio Pitch Changer
Load a song or recording, move the semitone slider and listen: the pitch changes while the tempo stays the same. Fine-tune in cents, compare with the original and download the result as WAV or MP3 — all on your device.
True pitch shift: the length and tempo stay the same.
How to use the Audio Pitch Changer
- Choose an audio file (or drop it on the box). It is decoded in your browser; nothing is uploaded.
- Set the pitch with the semitone slider or a preset, and use Fine tune for steps smaller than a semitone.
- Pick a mode: Keep tempo for a true pitch shift, or Change speed too for a faster/slower, higher/lower result.
- Press Play preview to listen. Switch between Shifted and Original to compare and click the waveform to jump.
- Export as WAV or MP3 with Export & download.
Semitones, cents and frequency ratios
In equal temperament each semitone changes frequency by the factor 21/12 ≈ 1.0595, so a shift of s semitones and c cents multiplies every frequency by 2(100·s + c) / 1200. In Change speed too mode the playback speed changes by the same factor, so the length becomes the original length divided by the ratio.
| Shift | Frequency ratio | Musical interval | Length in "change speed" mode (3:00 song) |
|---|---|---|---|
| +1 semitone | ×1.0595 | Minor second | 2:50 |
| +2 semitones | ×1.1225 | Major second (one whole step) | 2:40 |
| +3 semitones | ×1.1892 | Minor third | 2:31 |
| +5 semitones | ×1.3348 | Perfect fourth | 2:15 |
| +7 semitones | ×1.4983 | Perfect fifth | 2:00 |
| +12 semitones | ×2.0000 | Octave | 1:30 |
| −1 semitone | ×0.9439 | Minor second down | 3:11 |
| −12 semitones | ×0.5000 | Octave down | 6:00 |
How the pitch shift works
A true pitch shift is done in two steps. First the audio is time-stretched by the pitch ratio with WSOLA (waveform-similarity overlap-add): short, overlapping slices of about 46 ms are copied to the output, and each slice is chosen within ±11 ms of its ideal position so that its waveform lines up with the previous one. That changes the duration without changing the pitch. Then the stretched audio is resampled back to the original length with a windowed-sinc filter, which raises or lowers every frequency by the ratio. The result has the original tempo and a new pitch.
The resampler includes an anti-aliasing filter when the pitch goes up, so high frequencies are removed cleanly instead of folding back as distortion.
Common uses
- Singing and karaoke: move a backing track into a key that suits your voice.
- Playing along: match a recording to a guitar in standard tuning when the band tuned down a half step (shift +1 semitone, or −1 to go the other way).
- Fixing tuning drift: old tape recordings and vinyl rips often play a little sharp or flat; correct them with a few cents.
- Transcribing music: shift a fast bass line up an octave to hear it more clearly.
- Sound design: create deeper or chipmunk-style voices and effects.
Frequently asked questions
How do I change the key of a song without changing its speed?
Load the song, keep the mode on Keep tempo and move the semitone slider. One semitone equals one key step: +2 turns a song in C into D, −3 turns it from C into A. The length of the song stays the same.
What is the difference between Keep tempo and Change speed too?
Keep tempo time-stretches the audio first and then resamples it, so only the pitch changes. Change speed too simply plays the audio faster or slower, like a record at the wrong speed: higher pitch also means a shorter, faster track. The second mode has no processing artefacts but changes the tempo.
How many semitones should I shift to match my vocal range?
Each semitone is a small step; most singers find a song comfortable within ±2 to ±4 semitones of the original. +12 or −12 is a full octave. Use the preview to try a few values before you export.
Will the quality get worse?
Small shifts of a few semitones sound natural on most material. Large shifts of an octave can sound phasey or robotic, especially on complex mixes and voices, because time-stretching has to repeat or skip tiny pieces of the waveform. WAV export avoids any extra compression loss.
What are cents?
A cent is 1/100 of a semitone. Fine tune is useful to correct a recording that is slightly out of tune with A = 440 Hz, or to match a track to an instrument that cannot be retuned easily.
Why is MP3 export not working?
MP3 encoding uses a small encoder library that loads when you first export to MP3. If it cannot be downloaded (for example offline or behind a strict firewall), export as WAV instead and convert it later.
Is there a file size limit?
There is no fixed limit, but everything happens in your browser's memory. Songs of a few minutes are processed in seconds; very long recordings need more time and RAM, especially on phones.