五度圏
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Understanding the Circle of Fifths
Key Takeaways
- The Circle of Fifths arranges all 12 major and minor keys by the interval of a perfect fifth (7 semitones).
- Adjacent keys on the circle share all but one note, making them ideal for smooth modulations.
- Moving clockwise adds sharps; counterclockwise adds flats to the key signature.
The Circle of Fifths is one of the most important tools in Western music theory. It visually maps the relationships between all 12 major and minor keys, showing which keys are closely related, how many sharps or flats each contains, and which chords naturally belong together. This interactive diagram lets you explore these relationships by clicking on any key.
12 keys
All keys connected
Core Concepts
Perfect Fifth Interval
Moving clockwise, each key is a perfect fifth (7 semitones) above the previous. From C to G, G to D, D to A — this pattern continues through all 12 notes.
Key Signatures & Accidentals
C major has no sharps or flats. Each step clockwise adds one sharp (G has 1, D has 2, A has 3). Each step counterclockwise adds one flat (F has 1, Bb has 2, Eb has 3).
Relative Major & Minor
Every major key has a relative minor sharing the same key signature. C major and A minor both have no accidentals. The relative minor appears on the inner ring.
Common Chord Progressions
The I–IV–V progression uses three adjacent keys on the circle. For C major: C (I), F (IV), and G (V) sit side by side, explaining why this progression sounds natural.
Tips for Using the Circle
To find closely related keys, look at the two neighbors on either side — they differ by only one accidental.
Use the circle to transpose songs: shift every chord the same number of steps to change key.
Opposite keys (like C and F#) are tritone pairs and create maximum harmonic tension.
Memorize: sharps order is FCGDAEB, flats order is BEADGCF — they are each other's reverse.
This interactive Circle of Fifths runs entirely in your browser. No data is collected or transmitted. All music theory calculations are performed locally.