A scale is a set of notes that belong together. A key is a scale with a home note. Choosing a key decides which notes your bass, chords and melody will mostly use - and that is why everything in a track agrees when they share one.
The major scale
The major scale is built from a fixed pattern of tones (W) and semitones (H):
W - W - H - W - W - W - H
Starting on C gives C D E F G A B C - all white notes. Starting anywhere else, the pattern forces you to use sharps or flats to keep the distances right.
- G major - G A B C D E F# G. One sharp: F#.
- D major - D E F# G A B C# D. Two sharps.
- F major - F G A Bb C D E F. One flat: Bb.
The natural minor scale
The natural minor scale uses a different pattern:
W - H - W - W - H - W - W
Starting on A gives A B C D E F G A - all white notes again, because A minor and C major share the same notes. Other minor keys:
- E minor - E F# G A B C D. One sharp: F#.
- B minor - B C# D E F# G A. Two sharps: F# and C#.
- D minor - D E F G A Bb C. One flat: Bb.
- G minor - G A Bb C D Eb F. Two flats: Bb and Eb.
- C minor - C D Eb F G Ab Bb. Three flats: Eb, Ab and Bb.
Relative major and minor
Every major key shares its notes with a minor key, its relative minor, whose home note is three semitones lower. C major and A minor. G major and E minor. F major and D minor.
Same notes, different home - and a very different feeling. A progression that keeps returning to C sounds bright; the same chords returning to Am sound melancholy. Many songs move between the two, which is one of the easiest ways to shift mood without changing a single note of the key.
Major and minor in other forms
The natural minor is the starting point. Two variations matter in practice:
- Harmonic minor raises the seventh note by a semitone (in A minor, G becomes G#). This makes the fifth chord major (E instead of Em), giving a much stronger pull back home - and an exotic interval between the sixth and seventh notes.
- Melodic minor raises both the sixth and seventh going up. Common in jazz and in film music.
Key signatures
A key signature is the set of sharps or flats a key uses. Each major key has a unique signature, shared with its relative minor. Knowing the signature tells you instantly which notes are "in" the key.
The circle of fifths
Arrange the twelve keys in a circle, each a perfect fifth above the last, and you get the circle of fifths - one of the most useful diagrams in music.
- Going clockwise from C, each key adds one sharp: C - G (1#) - D (2#) - A (3#) - E (4#) - B (5#)...
- Going anticlockwise from C, each key adds one flat: C - F (1b) - Bb (2b) - Eb (3b) - Ab (4b)...
- The relative minor of each key sits alongside it: C with Am, G with Em, F with Dm.
It shows you, at a glance:
- Which keys are closely related. Neighbours on the circle differ by only one note, so moving between them sounds smooth. From C, the closest keys are G (add one sharp) and F (add one flat). From E minor, the relative major is G, and the closest related minor keys are B minor and A minor.
- Common progressions. Moving anticlockwise - G to C, D to G - is the strongest chord movement in tonal music.
- The chords in a key. The three major chords of a key are the key and its two neighbours: in C, those are C, F and G.
Interactive versions online let you click through the keys and hear the relationships.
Choosing a key
- For a singer, the key is set by their range. The same song in two keys a few semitones apart can sound strained in one and effortless in the other.
- Instruments have favourite keys. Guitar-based music often sits in E, A, D or G; brass in flat keys.
- Key affects the sound of electronic music too - the root note of a bassline determines how much sub-bass energy a track has. A track in F has its bass fundamental much lower than one in B.
Do this now
- Write out D minor and G minor using the formula W-H-W-W-H-W-W, then program each into your DAW as a one-octave run.
- Find the relative minor of G, D and Bb major.
- Using the circle of fifths, list the three major and three minor chords that belong to G major.
- Take your C major project and change the key to A minor without changing a note: find a way to make A feel like home (start and end the progression on Am, and put an A in the bass).