MP3 Transposer: Change the Key of a Song

This MP3 transposer changes the key of a song file without changing its speed: open an MP3, WAV or M4A, move it up or down, listen, and save it. Your file never leaves your device.

Open a song fileMP3, WAV, M4A, OGG or FLAC, up to 10 minutes. Drop it here or choose it. The file stays on your device.

How to change the key of a song file

  1. Open the song. Choose an MP3, WAV, M4A, OGG or FLAC file (up to 10 minutes), or drop it on the box. It opens in your browser; nothing is uploaded.
  2. Check the key. The tool estimates the key of the recording and shows two other likely keys. If you know the key, choose it yourself.
  3. Move it. Press − or + (one semitone each) or choose the new key, and press Play. Changes apply while it plays, so you can sing along and adjust.
  4. Practise with it. Slow the song down with Speed (the pitch stays the same) and loop a hard part with "Loop from here" and "Loop to here".
  5. Save it. Press Save as WAV to keep the new version. The file is made on your device, faster than playing it.

Worked example: a backing track that is too high

A singer has a backing track in E major, but the chorus strains at the top. Moving it down 2 semitones puts it in D major: every note of the track is 2 semitones lower, and the tempo is unchanged. If D is still high, one more semitone down gives D♭ major. The chords for a guitarist or pianist playing along move by the same amount: paste them into the chord transposer and press − twice.

Tips for the best sound

Small changes sound best

Every pitch-shifting method colours the sound a little, and the effect grows with the size of the change. A change of a few semitones usually sounds natural; a whole octave much less so.

Try formant correction on vocals

If the singer sounds thin after moving up, or boomy after moving down, turn on "Keep voices natural". For instrumental backing tracks it often makes no difference.

Slow it down to learn it

At 75% speed a fast passage is easier to hear and play, and the key stays the same, so you can play along on your instrument. Loop the part until it feels easy, then go back to 100%.

Keep the chords in step

When you move a recording by some semitones, move the chord sheet by the same number in the chord transposer, or use a capo: the capo calculator shows which fret gives the new key with easy shapes.

How it works

The pitch is changed with Signalsmith Stretch, an open-source audio library that keeps the timing while it moves every note, running inside your browser. The key is estimated from the recording itself: the tool measures how strong each of the 12 notes is across the song and compares the result with the typical note pattern of each of the 24 major and minor keys. Both run on your device, so the song is never uploaded.

Frequently asked questions

How do I change the key of an MP3?

Open the song file above, press + or − to move it up or down one semitone at a time (or choose the new key), and press Play to check it. When it sounds right, press Save as WAV. The speed stays the same unless you change it.

Is my song uploaded anywhere?

No. The file is opened, analysed and changed inside your browser, on your device. Nothing is sent to a server, and the page keeps working without an internet connection once it has loaded.

How many semitones should I move a song for my voice?

A small change is often enough: try one or two semitones down if the high notes strain, or up if the song feels low and dull. To work it out exactly from your range, use the guide to finding the best key for your voice.

Does changing the key change the speed?

No. The pitch and the speed are separate: the song keeps its tempo when you change the key, so this works as a song key changer (a pitch changer), not a speed changer. You can also slow a song down (for practice) without changing its pitch with the Speed setting.

How accurate is the key it finds?

It is an estimate. The tool measures how strong each of the 12 notes is across the whole recording and compares that with the typical pattern of each major and minor key (the Krumhansl–Kessler profiles). Songs that move between keys, or stay on one chord, can fool any key finder, so the tool shows the other likely keys and lets you set the key yourself.

Why does it save a WAV file and not an MP3?

A WAV file keeps the full quality, and every phone, computer and audio app can play it. It is larger than an MP3 (about 10 MB per minute in stereo). If you need an MP3, any audio converter can make one from the WAV.

What does "keep voices natural" do?

Moving a recording up makes voices sound thinner, and moving it down makes them sound deeper, because their tone colour (the formants) moves too. Formant correction keeps the tone colour where it was. Try it on and off and keep whichever sounds better for your song.

Can I change the key of a song on YouTube or Spotify?

Not with this tool: it works with audio files on your device. Use recordings you have the right to use, such as your own recordings or backing tracks you bought.

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