Relative key

The same notes, a different centre

The page Circle of fifths describes it like this: every major key has a relative minor key with an identical key signature. The minor key begins three semitones below the major key. That explains why the key signature alone never tells you whether a piece is in major or minor. The exercise page Key Signatures says it explicitly: C major and A minor have no sharps or flats, G major and E minor one, F major and D minor one. The ending and the beginning of the piece decide.

C major and A minor share all seven notes, only the home note differs. That is what the home page says in the section on the circle of fifths. By “home note” the tonic is meant, the note to which everything relates. The natural minor scale is therefore a major scale that begins on the sixth degree.

All 15 pairs

On the circle of fifths the inner ring shows the relative minor for every major key. The page Circle of Fifths lists the pairs up to A♭ major, the following table adds the rest.

A simple rule of calculation: from the major key you go down a minor third, so three semitones. From G major it becomes E minor, from E♭ major C minor. Conversely a minor third up from the minor key leads to the relative major.

Relative key or parallel key?

The two terms are often confused. The page Circle of Fifths explains the difference with the example C major: the relative key is A minor, with the same notes and a different centre. The parallel key is C minor, with the same tonic and three additional flats. According to the page the change to the parallel key is a much stronger emotional contrast, because three notes change at once. The change to the relative key, by contrast, changes not a single note.

The relative key in a piece

Because no notes change, the relative key is the most natural route for a change of key. For a song structure of your own the home page suggests writing the bridge in the relative minor. In a sheet from the archive the change can be read off:

Guitar

• Etüde Nr. 7 Matteo Carcassi, op. 60 No. 7 · guitar · 2 pages

  Bars 1 to 8 carry chord symbols in A minor, in bar 2 a G♯ appears. In bar 9 a section begins with the chords C, Dm, G, C, so in the relative key C major. The key signature stays empty in both parts. From bar 16 E and Am lead back to A minor.

Common mistakes

• Confusing relative and parallel: Relative keys share the key signature, parallel keys the tonic.
• Taking the key signature for the ending: The same key signature can mean major or minor. Check the final note and the last chord.
• Counting in the wrong direction: From major you go three semitones down, not up. If you go three semitones up, you land on the tonic of a quite different key.