Circle of fifths

A perfect fifth is an interval of seven semitones, like C up to G. Keep stepping up by fifths from C and you pass through all 12 notes before landing on C again, which is what closes the circle:

C, G, D, A, E, B, F# (or Gb), Db, Ab, Eb, Bb, F, and back to C.

Clockwise from C, each key has one more sharp than the last, up to six at F#: G major has F#, and D major adds C#. Counterclockwise from C, each key adds a flat, up to six at Gb: F major has Bb, and Bb major adds Eb. F# major and Gb major sit together at the bottom because they are the same notes spelled two ways. Most diagrams put each key’s relative minor on an inner ring, so A minor sits inside C and E minor inside G.

Neighbors on the circle share six of their seven notes. G major is C major with F raised to F#, and nothing else changes. That closeness is why songwriters use the circle as a map:

• Chords for a key. Your key and its two neighbors give the three major chords, I, IV and V. In C that is C, F and G. The three minor keys inside them give ii, vi and iii: Dm, Am and Em.
• Chords that pull home. Stepping counterclockwise sounds like resolving. Am, Dm, G, C (vi, ii, V, I) walks around the circle into C.
• Key changes. Moving to a neighboring key sounds smooth. A key from the far side of the circle sounds like a jolt.

Read counterclockwise, every step is a fourth up, which is why the same diagram also goes by the circle of fourths.

You usually meet the circle in the first theory lesson on key signatures. The full table of keys with their sharps and flats, and how to use it for writing, is in how to use the circle of fifths to write songs. To hear a walk around the circle, pick C major in the free online chord player and play Am, Dm, G, C.