How the Circle of Fifths Works
The circle of fifths is a diagram of the twelve major keys (and their minor partners) arranged so that neighboring keys are as closely related as possible. It is one of the most useful pictures in music theory because so many questions about keys and chords can be answered by looking at it.
How it is built
Start at C at the top. Move clockwise by a perfect fifth (seven semitones, or five letter names) each step: C, G, D, A, E, B, F♯, then C♯ (or D♭), A♭, E♭, B♭, F, and back to C. The twelve steps use all twelve notes exactly once, which is why the diagram closes into a circle.
Key signatures
Each clockwise step adds one sharp to the key signature: C has none, G has one (F♯), D has two (F♯ and C♯), A has three, E has four, B has five and F♯ has six. Each counterclockwise step adds a flat: F has one (B♭), B♭ has two, E♭ three, A♭ four, D♭ five and G♭ six. The sharps always arrive in the order F C G D A E B, and the flats in the reverse order B E A D G C F, which is why a mnemonic such as “Father Charles Goes Down And Ends Battle” works for sharps. F♯ and G♭ are the same notes written two ways, so the circle can be read as having sharps on one side and flats on the other, meeting at the bottom.
Relative minors
Every major key shares its key signature with a minor key, called its relative minor, whose tonic is the sixth note of the major scale (or, equivalently, three semitones lower). C major’s relative is A minor; G major’s is E minor; D major’s is B minor. On the circle the minor keys form an inner ring directly below their relative majors. Two keys with the same signature use exactly the same seven notes, but they feel different because the home note is different.
Neighboring keys share notes
Moving one step around the circle changes only one note of the scale. C major and G major share six of their seven notes (only F becomes F♯). This is why changing key to a neighbor, a common way to lift a song or lead into a new section, sounds smooth, while jumping to the opposite side of the circle sounds like a big change.
Finding the chords of a key
The six main chords of a major key sit together on the circle: the key itself (I) and the keys on either side of it, one step clockwise (V) and one step counterclockwise (IV), plus the minor chords on the inner ring below them (vi, iii and ii). In C major that gives C, G and F with A minor, E minor and D minor. The seventh chord of the scale (B diminished in C) is the odd one out and is used less often. The circle of fifths tool highlights these chords for each of the 24 keys and plays them.
Using it for songwriting and transposing
- Writing a progression: pick a key and use chords from its cluster on the circle. Almost any combination of them sounds like it belongs together. Try the chord progression builder or read about common progressions.
- Strong movement: moving a chord counterclockwise by a fifth (G to C, or D to G) creates a strong feeling of resolution, which is why the V to I cadence is so central. Chains of such moves, like Dm7 to G7 to Cmaj7, are the backbone of jazz harmony.
- Transposing: to move a song to a singer’s range, shift every chord the same number of steps around the circle, or the same number of semitones. The relationships between chords are unchanged.
- Reading a key signature: count the sharps or flats to find the major key; the relative minor is a minor third below. Then look at the last chord or the melody’s resting note to decide between the two. See how to find the key of a song.