Song Key Finder

Find the key of a song from an audio file or by letting the finder listen through the microphone, then get the guitar chords in that key and the easiest capo.

Drop a song, play the demo, or press Listen and play it out loud. You get the key, then the chords to play it on guitar.

Find the key

Runs on this device

MP3, WAV, M4A, FLAC or OGG, up to 20 at once. Files are read by your browser, never uploaded. Only on Spotify or YouTube? Press Listen and play the song out loud.

How to find the key of a song

Drop an audio file on the box (MP3, WAV, M4A, FLAC or OGG) or tap it to pick files from your phone; you can add up to 20 songs and they are analysed one after another. No file to hand? Press Listen: the finder hears the song through the microphone for 20 seconds while you play it from a speaker. On a desktop Chrome or Edge you can choose Tab audio instead and share the browser tab that plays the music, which gives a cleaner signal than a microphone.

Everything happens in your browser. The audio is decoded and analysed on your own device and is not uploaded, stored or sent anywhere, so it works with unreleased demos and rehearsal recordings too.

Reading the result

The big name is the key the finder thinks fits best, with its Camelot code next to it. The confidence word tells you how clearly the music pointed there. When it is only fairly sure, a second guess appears: usually the relative major or minor (C major and A minor share every note) or the key a fifth away. Play the home chord of each guess along with the chorus; the right one sounds settled, the wrong one leaves the song hanging.

If a recording is tuned away from standard pitch by 15 cents or more (older records, songs sped up or slowed down, some bands tune to A = 432 Hz), the result says how far, so you can retune with the guitar tuner until your open strings match the record.

From the key to your guitar

Under the result you get the seven chords of the key, I to vii°, as diagrams you can tap to hear. In practice most songs use four of them, and the I, IV and V chords carry the most weight.

The capo line picks the lowest capo fret that turns the key into open-chord shapes: a song in A♭ major becomes capo 1, G shapes; B♭ major becomes capo 1, A shapes. The other capo buttons show every open-shape option up to the 7th fret, and the capo calculator covers the rest. The transpose buttons move the song up or down a semitone at a time to suit your voice; chords, capo and links follow.

Then go deeper: the key page has progressions and the fretboard map in that key, the scale page shows where to solo, and the circle of fifths shows how the key relates to its neighbours (all keys are listed on the keys page).

How accurate is it?

On 141 human-labelled loops from the Freesound Loop Dataset that were never used to tune it, the finder named the exact key 67 % of the time, and the exact key or a close neighbour (relative key or a fifth away) 82 % of the time. These figures were measured on short loops only, not on full songs, and full songs can score differently.The accuracy page has the full test, the confidence intervals and where it goes wrong.

Need the tempo as well? The BPM finder reads the same file and adds a practice click at the song tempo.

FAQ

Is my song uploaded anywhere?

No. The file is decoded by your browser and analysed in a background thread on your own device. Nothing is sent to a server and nothing is stored after the page closes.

Why does it say A minor when the chord sheet says C major?

They share all seven notes (relative keys), so the same song can be heard either way. Look at the chord the song keeps coming home to: if it ends on Am, call it A minor; if it rests on C, call it C major. The second guess often shows the other one.

Why is the key a fifth away from what I expected?

Songs that lean hard on the V chord (G in C major) sometimes read as the key of that chord. Try the second guess, or play the I chord along with the chorus: the right key sounds settled.

Can I change the key to suit my voice?

Use the transpose buttons under the result. The chords, the capo suggestion and the key page link all follow, so you can find a key you can sing and the easiest way to play it.

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