How to Find the Key of a Song

The fast way: use a key finder

Open the free Key & BPM Finder and drop in an MP3, WAV, FLAC, M4A, AAC or OGG file. It analyses the song in your browser, so the file never leaves your computer, and shows:

• The key, such as A minor, with a confidence reading.
• The relative key (C major for A minor), because songs often sit between the two.
• The Camelot number (8A for A minor), the code DJs use for harmonic mixing.
• Clear key changes with their time, so a last-chorus lift shows where it happens.

It corrects for tuning first, so a record cut a little sharp or flat still reads as the right key. A band tuned down a half step reads as the key it sounds in, a semitone below the chord shapes. You also get the tempo in the same pass (more on that in how to find the BPM of a song).

How to find the key by ear

A finder is quick, but knowing how to check it makes you a better musician, and it settles the cases where software hesitates. You need a keyboard, a guitar or a free piano app.

1. Hum the home note

Play the chorus and stop it at the end of a phrase. Hum the note that feels finished, the one the melody wants to land on. Find that note on your instrument. That is your best guess for the key’s root, also called the tonic.

2. Major or minor?

Play the root note, then the major chord built on it, then the minor chord, while the song plays. One will sit inside the song; the other will clash. Bright and settled usually means major. Darker, sadder or tense usually means minor.

3. Check the chords against the key

Every major key has seven chords that belong to it. In G major they are G, Am, Bm, C, D, Em and F♯dim. A minor key uses its relative major’s set: E minor uses the same seven chords as G major. If the song’s chords mostly come from one set, you have the key. A borrowed chord here and there is normal; a chord that clashes all the way through means you should test the next candidate.

4. Listen to the first and last chords, and the bass

Many songs start and end on the key’s home chord, and the bass often lands on the root at the end of the chorus. They are clues, not rules: plenty of songs start somewhere else or fade out mid-progression. If the bass is hard to hear, isolate the bass and listen to it on its own.

Why a key finder shows two keys

Every major key shares its notes with a minor key, its relative minor. C major and A minor use exactly the same seven notes, so a song built from them can read as either. The difference is where the song comes to rest: if it keeps resolving to C, it is in C major; if it keeps resolving to A, it is in A minor. That is why the finder always shows the relative key next to the answer, and why your ears get the final say.

Songs that change key

Some songs lift a semitone or a tone for the last chorus, and some move to a new key for the bridge. A single key on a website will miss that. The finder scores the song every few seconds and shows a clear key change with its time, such as a lift for the last chorus. A move between close keys, a fifth or a tone apart, can still read as one key, so check the bridge by ear.

Capos, tunings and chord sites

Guitar chord sites often show the shapes a player uses with a capo, not the sounding key. A song played with G shapes and a capo on the 2nd fret sounds in A. Bands that tune down a half step sound a semitone lower than the shapes suggest. If a chord chart and the record disagree, trust the record, and use the finder or the steps above to hear where it really sits.

What to do once you know the key

• Sing it in your range. Move the whole song up or down with the free speed and key player without changing its speed.
• Mix it as a DJ. Tracks with the same Camelot number, or one number apart with the same letter, mix without clashing.
• Learn the part. Split the song into stems, solo the instrument you are learning, and loop the hard bar. How to learn any bassline by ear walks through it.

Frequently asked questions

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