How to find the key of a song

Knowing a song's key is the first step to playing over it: it tells you which notes belong, which scale to start with, and which chords to expect. You can work it out by ear in a few minutes with these clues — no perfect pitch needed.

1. Find the note that feels like home

Every song has a note it keeps resolving to — the one that sounds finished when the song stops on it. Play along with the track and hunt for it on one string, low E or A, until you find a note that never clashes and that the song seems to "land" on at the end of phrases. That note is almost always the key's tonic.

A quick test: stop the song on its last chord and hum a note. Most people hum the tonic without trying.

2. Check the first and last chords

Most songs start on their home chord, and most of them end on it. If a song starts on G and ends on G, and the note you found in step 1 is G, you're in G — major or minor, which is next.

Be careful with the start: plenty of songs open on another chord for effect. The last chord, and the chord the chorus resolves to, are the more reliable clues.

3. Major or minor?

Play the tonic's major chord, then its minor chord, along with the song. One will sound right, the other will clash — usually obviously. A major key sounds bright and settled; a minor key darker or more serious.

Every major key has a relative minor that uses the same notes: C major and A minor, G major and E minor. If the chords fit both, ask which chord feels like home: if it's the C chord, you're in C major; if it's Am, you're in A minor.

4. Look for the giveaway: the dominant 7th

A dominant 7th chord — E7, A7, D7 — almost always points to the chord a fourth above it. E7 pulls to A or Am, D7 to G, A7 to D or Dm. If you hear a 7th chord resolving somewhere, where it resolves is very likely the key. It works for minor keys too: their V chord is usually major (E or E7 in A minor), so E7 falling to Am points straight at A minor.

5. Confirm with the chords

Write down the chords you hear and check them against the key's chords. In a major key they are: I, ii, iii, IV, V, vi and vii° — in G major, G, Am, Bm, C, D, Em and F#°. If most of the song's chords are on that list, you've found the key. A chord or two from outside is normal: songs borrow chords all the time.

When you know the key, the scale to start improvising with follows: the major pentatonic of a major key, the minor pentatonic of a minor one. The guide to improvising over any song takes it from there.

The fast way

Working out the key by ear is a skill worth having — but when you just want to play, easyimprov does it in about half a minute: upload a track and it finds the key, the tempo and every chord, bar by bar, and shows you what to play over each one.