How to Find the Key of a Song (By Ear and From Chords)

By Wikum · September 15, 2026 · 4 min read · Theory

Knowing a song's key is like knowing which neighbourhood you're in. Once you know it, you can guess the chords before you hear them, know which scale to use for a solo, and find a capo position in seconds. Here are four ways to find the key, from easiest to most musical.

Method 1: look at the chords

If you have the chords, the key is usually obvious once you know the chord families. Every major key has six common chords: I, ii, iii, IV, V and vi. Look for the key whose family contains all (or nearly all) of the song's chords.

Example: D – A – Bm – G. Which family has D, A, Bm and G? D major: D, Em, F#m, G, A, Bm. So the song is in D major, and the progression is I–V–vi–IV.

You can type chords into the key finder to check, and it'll show the Roman numerals too.

Method 2: the first and last chord

Songs usually start, and very often end, on the home chord. The end of the chorus is the best clue: listen for the chord that feels like a full stop, a resolution. That chord is almost always the key. It's not a rule — plenty of songs start on IV or vi to create interest — but it's correct more often than not.

Method 3: hum the home note

This is the method musicians use with no chords at all.

1. Listen to the song for a while.
2. Pause it in the middle of a line, and hum the note that would make the song feel “finished”. Most people can do this instinctively.
3. Find that note on your guitar. Play single notes on the low E or A string until one matches your hum.
4. Strum the major and minor chord on that note while the song plays. The one that fits is the key.

Practise with songs where you already know the key, and this becomes surprisingly reliable within a few weeks.

Method 4: follow the bass

The bass line usually plays the root of each chord. Find the bass notes on your low E and A strings while the song plays. The note the bass keeps returning to — especially at the ends of sections — is the key note.

Major or minor?

Once you have the home note, decide whether the key is major or minor. Play the major chord and the minor chord on that note along with the recording. The wrong one will clash obviously. Broadly, major keys feel bright and settled; minor keys feel darker or more serious — but plenty of upbeat dance songs are in minor keys, so trust your ears over the mood.

Relative keys: same chords, different home

Every major key shares its chords with a minor key, called its relative minor. C major and A minor both use C, Dm, Em, F, G and Am. What decides the key is which chord is home.

The relative minor's root is the 6th note of the major scale — or simply three frets below the major root.

Clues that point to a minor key

• The song starts and ends on the minor chord.
• There's a major V chord, such as E or E7 in A minor. Minor keys “borrow” this from the harmonic minor scale to create a stronger pull home. If you see Am, Dm and E together, you're almost certainly in A minor.
• The verse sits on the minor chord for a long time.

When chords don't fit any key

Rock and pop love borrowed chords. In G major, you'll often find F (bVII), Cm (iv) or Bb (bIII). These come from G minor or G Mixolydian and add colour. If all but one chord fits a key, that's usually the key, and the outsider is a borrowed chord. Songs can also modulate — change key — often moving up a semitone or tone for a final chorus.

Putting it to use

Once you know the key, open the scale finder to see the notes on the fretboard and try improvising a melody, or use the transposer to move the song to a key that suits your voice.