Minor scales

There is one major scale pattern and three common minor ones. That is not fussiness — each form solves a real problem the others create.

Natural minor

The natural minor takes the major scale and flattens the third, sixth and seventh degrees.

Pattern: T – S – T – T – S – T – T

A natural minor: A B C D E F G A — no accidentals, which is why it is the standard first example.

Relative minor

That last point is the important one. A minor and C major contain identical notes. They are relative keys and share a key signature.

What separates them is which note behaves like home. Centre the music on C and it sounds major; centre it on A and it sounds minor. Same pitch set, different gravity.

To find any relative minor: go down a minor third from the major tonic — or up a sixth, which is the same place. G major's relative minor is E minor. F major's is D minor.

Harmonic minor

Natural minor has a problem. Its seventh degree sits a whole tone below the tonic, so it does not lean into it the way a major key's leading tone does. Cadences sound weak.

The harmonic minor fixes this by raising the seventh degree by a semitone.

A harmonic minor: A B C D E F G♯ A

That G♯ is a leading tone again, and the chord built on the fifth degree becomes major, which gives the strong resolution the natural minor lacked. Hence harmonic — the change exists to serve the harmony.

The side effect is a tone-and-a-half gap between F and G♯. It is a distinctive sound, and a large part of why harmonic minor is so associated with Eastern European and Middle Eastern music.

Melodic minor

That augmented-second gap is awkward to sing. Melodic minor solves it by raising the sixth as well as the seventh — but only going up.

A melodic minor ascending: A B C D E F♯ G♯ A A melodic minor descending: A G F E D C B A (back to natural minor)

The classical rule is that it reverts on the way down, because the leading tone is only needed when climbing towards the tonic. Jazz generally keeps the raised sixth and seventh in both directions — often called the jazz minor.

Which to use

You do not choose one and stick with it. A single piece in A minor will freely use G, G♯ and F♯ depending on what is happening at that moment. The three forms are better understood as one key with a flexible upper region than as three separate scales.