Parallel, relative minor, and harmonic minor Keys

New terminology appears when you start digging into the relationship between keys, like parallel, relative minor, and harmonic minor keys. They sound similar enough, but they describe very different relationships. Getting these concepts into my noggin helped me be more intentional with my harmony and songwriting decisions.

Parallel keys

Parallel keys enable bold shifts; they share the same home note but speak different emotional dialects.

If a chord progression suddenly takes a hard left-turn and feels heavier/brighter, but still resolves to the same root, you are probably in a parallel key.

Parallel keys both start on the same tonic but use different note sets for their scales.

Changing between parallel keys can feel bold, emotional, and cinematic. You are shifting the emotional colour and the note set at the same time, while keeping the same tonal centre.

A song that flips from feeling hopeful to bleak without changing its sense of home is likely shifting between parallel major and minor keys.

Example of Parallel Keys:

C major ↔ C minor
- both have C as their home (tonic/root) note, but the scale itself changes; C major has a major third, C minor has a minor third, plus a few other altered notes.
  - C major: C – D – E – F – G – A – B
  - C minor: C - D - E♭ - F - G - A♭ - B♭

Every key has its parallel

Rule of thumb: Are you in a major key? Keep the note name the same and flip to minor, or vice versa.

C major → C minor
F major → F minor
A♭ major → A♭ minor
B major → B minor

Relative minor

Relative minor keys enable subtle shifts; they share identical scales but differ with their starting point, giving each its own emotional anchor.
- If a chord progression suddenly sounds a bit darker, but still familiar, you are probably dealing with a relative minor key.

Each major key has its relative minor; they share the same notes + key signature, but from a different tonic/root/home note. Despite sharing the same scales, they feel different because they resolve to a different place.

Shifting between relative keys enables you to change the mood without introducing new notes; a bright major-key verse can slip into its darker relative-minorkey chorus without sounding jarring.

Example of Relative Keys:

C major ↔ A minor
- Same notes, only the white keys on the piano; no sharps, no flats.
- They differ only by their starting point (tonic):
  - C major: C – D – E – F – G – A – B
  - A minor: A – B – C – D – E – F – G
- In A minor, everything wants to resolve to A.
- In C major, everything wants to resolve to C.

Finding the relative key in 3 easy steps

To find the relative to any major key:

Count three semitones down from the tonic of the major key, and whatever note you’re on, that’s the major key’s relative minor.
- Example: C major - From the root note of C, count down 3 semitones (half-steps): B→B♭→A. Therefore, A minor is the relative minor.

To find the relative to any minor key:

Count three semitones up from the tonic of the minor key, and whatever note you’re on, that’s the minor key’s relative major.
- Example: E♭ minor - From the root note of E♭, count up 3 semitones (half-steps): E→F→G♭. Therefore, G♭ major is the relative major.

harmonic minor

Harmonic minor keys enable stronger resolution; they keep the same tonic as the minor key, but alter one note to increase harmonic tension.
- If a minor-key progression suddenly feels more dramatic and more determined to resolve, you are probably hearing harmonic minor.

With the natural minor, the music sounds dark, but it doesn’t resolve strongly; the tension feels weak when trying to land back on the tonic.

This is where harmonic minor comes in; it’s just a small modification to change how minor-key harmony resolves.

To change diatonic minor to harmonic minor:

Start with a natural minor key.
Raise the 7th note by one semitone. That’s it. Everything stays the same except the 7th note.

Example of harmonic minor:

A natural minor: A – B – C – D – E – F – G
A harmonic minor: A – B – C – D – E – F – G#

That single raised note has a big effect on the chords built from the scale.

Why harmonic minor exists

In a natural minor key, the chord built on the fifth note is minor. In the key of A minor, that chord is E minor. The weaker pull back to the tonic with minor dominant chords is due to a lack of leading tone; the resolution feels less final.

By raising the 7th note, the dominant chord becomes major. In A harmonic minor, the dominant chord becomes E major.

This major dominant creates a sense of tension, and a stronger pull back to the tonic, which is A. For this reason, harmonic minor feels more dramatic and deliberate.

Rules of thumb