Interactive Circle of Fifths - Music Theory Reference

How to use this tool

1. Select an outer major-key segment or an inner relative-minor segment.
2. Use the relative and parallel key links to switch modes and compare their triads.
3. Choose a chord chip or play action to hear browser-synthesized audio.

Understanding the circle of fifths

Moving clockwise adds one sharp to the key signature. Moving counter-clockwise adds one flat. Keys adjacent on the circle are closely related and sound harmonically similar.

Why a perfect fifth?

A perfect fifth (7 semitones) is the most consonant interval after the octave, arising from the simple frequency ratio 3:2. Stacking twelve perfect fifths (each multiplying the frequency by 3/2) returns to the starting note after 7 octaves in just intonation. In equal temperament (which slightly shrinks each fifth so they close perfectly), this creates the 12-note chromatic scale arranged in a circle - hence "circle of fifths." Adjacent keys on the circle share all but one note, which is why they sound so harmonically similar and modulating between them is seamless.

Key signatures

Inner ring: relative minor keys

The inner ring shows the relative minor for each major key. They share the same notes (key signature) but start on a different root.

Select an inner segment to view its natural-minor (Aeolian) triads. The key panel also links to the relative and parallel major or minor, so you can move between keys that share a key signature and keys that share a tonic. The combined F♯/G♭ major segment spells its relative minor as E♭ minor; D♯ minor is the enharmonic spelling with six sharps.

Chord progressions via the circle

Moving counterclockwise (down a fifth, or up a fourth) creates the ii–V–I motion central to jazz. In C major: Dm7 (ii) -> G7 (V) -> Cmaj7 (I) moves two steps counterclockwise on the circle. This motion is the most resolved, satisfying harmonic cadence in Western music. Composers exploit the full circle for key modulations: moving clockwise lands in a brighter key; counterclockwise in a darker key.

Parallel and relative minors

Each major key has two associated minor keys:

• Relative minor: shares the same key signature. Found 3 semitones below the major root (or 6 steps clockwise on the inner ring). C major -> A minor.
• Parallel minor: shares the same root but has a different key signature. C major -> C minor (3 flats). Switching between parallel major and minor creates a dramatic color shift while keeping the same tonal center.

Using the circle for songwriting

• Smooth modulation: moving one step clockwise or counterclockwise is the smoothest key change possible. Pop songs often modulate up a half step for the final chorus for emotional impact.
• Tritone substitution: chords directly opposite on the circle (a tritone apart) can substitute for each other in jazz. G7 and D♭7 are tritone substitutes and both resolve to Cmaj7.
• Borrowed chords: "borrowing" a chord from the parallel minor (the key on the same root but opposite mode) adds color. In C major, the ♭VII chord (B♭ major) is borrowed from C Mixolydian and is common in rock.

Hear chords and scales

After selecting a key, choose a diatonic chord chip to hear that triad, or use the tonic, scale, and cadence actions to hear a short pattern. The audio is synthesized locally in your browser with Web Audio oscillators; no samples or audio files are downloaded, and sound starts only after you choose a playback action. The major scale and I–IV–V–I cadence follow the selected major key. In natural-minor mode, the scale and cadence use the Aeolian notes and i–iv–v–i triads. Use Stop playback to end a pattern early.