The Circle of Fifths
The twelve-note arrangement that shows key signatures, relative keys, and the harmonic relationships composers use to move between keys.
The circle of fifths is a diagram that arranges the twelve pitch classes of Western music in order of ascending perfect fifths. Starting from C and moving clockwise by fifths (C, G, D, A, E, B, F-sharp, C-sharp), each new key adds one sharp to its key signature; moving counterclockwise by fifths (C, F, B-flat, E-flat, A-flat, D-flat, G-flat) adds one flat. The circle therefore encodes the complete system of key signatures in a single picture.
The correspondence with key signatures is exact. The order of sharps is F, C, G, D, A, E, B, and the order of flats is its reverse, B, E, A, D, G, C, F:
| Major key | Sharps/flats | Relative minor |
|---|---|---|
| C major | none | A minor |
| G major | 1 sharp (F♯) | E minor |
| D major | 2 sharps (F♯, C♯) | B minor |
| A major | 3 sharps | F♯ minor |
| F major | 1 flat (B♭) | D minor |
| B♭ major | 2 flats (B♭, E♭) | G minor |
| E♭ major | 3 flats | C minor |
The circle also shows relative keys: each major key has a relative minor sharing the same key signature, found a minor third below — C major with A minor, G major with E minor, and so on. Because the keys adjacent on the circle differ by only one note, they are harmonically close: chords and scales from neighboring keys share most of their notes, which is why modulations to adjacent keys sound smooth and why the strongest harmonic motion in tonal music, the dominant–tonic cadence, moves down a fifth — from G to C, from D to G — the shortest path around the circle.
The circle is a practical tool for composers and improvisors. Common progressions can be read directly: the pop/rock progression I–V–vi–IV walks around the circle, and the classic ii–V–I jazz cadence approaches the tonic from two fifths away. Chord movement by fifths is the default currency of tonal harmony, and the circle of fifths is its map. The chart also handles enharmonic equivalence: at the bottom, F-sharp and G-flat are the same pitch but notated differently depending on context, which is why the circle is often drawn with both names. It connects naturally to the other foundation of musical structure, the rhythm laid out by time signatures and meter, in the sense that both organize the two axes — pitch and time — along which music is written.