Scales, keys and modes

A scale is a set of notes that sound at home together, defined by a pattern of steps. Pick a starting note (the root or tonic), apply the pattern, and you have a key.

Major and minor

The major scale pattern is W-W-H-W-W-W-H, where W is a whole step (2 semitones) and H is a half step (1). From C it gives C D E F G A B: all white keys. The natural minor scale is W-H-W-W-H-W-W. From A it gives A B C D E F G: the same white keys, starting from A.

That's no coincidence. C major and A minor share all their notes; they are relative keys. Every major key has a relative minor three semitones below its root. Keys with the same root but a different scale (C major and C minor) are parallel keys.

Scale degrees

We number the notes of a scale 1 to 7 and compare them to the major scale. Natural minor is 1 2 ♭3 4 5 ♭6 ♭7: its 3rd, 6th and 7th are a semitone lower than in major. These numbers let you talk about any key at once: “the ♭3” means C in A minor and F in D minor.

Modes

Start the major scale's step pattern from each of its seven notes and you get seven modes. Each mode has one characteristic note that gives it its flavor. The easy way to hear them: play only white keys, starting and ending on a different letter, over a drone of that letter.

The seven modes

Mode	White keys from	Formula	Character	Where you'll hear it
Ionian (major)	C	1 2 3 4 5 6 7	Bright, resolved	Major-key cumbia, roots reggae
Dorian	D	1 2 ♭3 4 5 6 ♭7	Minor but hopeful, soulful	Reggae and dub vamps, dub techno, deep house
Phrygian	E	1 ♭2 ♭3 4 5 ♭6 ♭7	Dark, tense, Spanish-tinged	Dark minimal and acid lines
Lydian	F	1 2 3 ♯4 5 6 7	Floating, dreamy	Pads and ambient intros
Mixolydian	G	1 2 3 4 5 6 ♭7	Major but bluesy, earthy	Cumbia and Latin melodies, dominant chords
Aeolian (natural minor)	A	1 2 ♭3 4 5 ♭6 ♭7	Dark, melancholy	The default for dub and techno
Locrian	B	1 ♭2 ♭3 4 ♭5 ♭6 ♭7	Unstable, rarely home	Occasional dark riffs

Three more scales you need

Harmonic minor (1 2 ♭3 4 5 ♭6 7): natural minor with the 7th raised. That one change creates a major V chord (E major in A minor) that pulls hard back home. Minor-key cumbia depends on it.
Phrygian dominant (1 ♭2 3 4 5 ♭6 ♭7): the fifth mode of harmonic minor. Spanish, Middle Eastern, desert heat. You'll hear it in Peruvian chicha guitar lines and over V7 chords in minor keys.
Pentatonic scales have five notes and no semitones, so nothing clashes. Minor pentatonic (1 ♭3 4 5 ♭7) is the safest scale in music: dub basslines, melodica tunes, chicha guitar riffs and techno hooks. Major pentatonic (1 2 3 5 6) is sunny and folk-like, common in cumbia and Andean melodies. Add a ♭5 to minor pentatonic and you get the blues scale.

How each genre uses scales

Dub: natural minor, Dorian and minor pentatonic for basslines and melodica. Roots reggae also uses plenty of major keys.
Minimal techno: often one note, a root and its octave, or a Phrygian or minor fragment. What matters is that the kick, bass and any stab agree on a root, so tune your kick to the key.
Cumbia: major keys for classic cumbia, harmonic minor for minor cumbia, Mixolydian color in melodies, pentatonics in chicha and Andean styles. Melodies are often doubled a 3rd or 6th apart.