The Circle of Fifths Understand Key Signatures and Accidentals

The circle of fifths is a fundamental tool in music theory, showing the relationship between all 12 major and minor keys. It is constructed as a circle, where each step clockwise corresponds to a perfect fifth up (five notes), and each step counterclockwise corresponds to a perfect fifth down.

Structure

In the center of the circle is the key of C major (no accidentals). Moving clockwise, one sharp (#) is added for each fifth: C → G → D → A → E → B → F# → C#. Moving counterclockwise, one flat (♭) is added for each fifth: C → F → B♭ → E♭ → A♭ → D♭ → G♭ → C♭.

Accidentals and keys

• Clockwise (sharps): C, G, D, A, E, B, F#, C#
• Counterclockwise (flats): C, F, B♭, E♭, A♭, D♭, G♭, C♭

Each major key has a relative minor key, which shares the same accidentals. The relative minor key is always three semitones (a minor third) below the major key. For example: C major ↔ A minor, G major ↔ E minor.

Using the circle of fifths

1. Finding accidentals: Quickly identify how many sharps or flats a key has.
2. Modulation: Change key to a closely related key in composition.
3. Chord progressions: Understand why certain chords naturally follow each other.
4. Relative keys: Switch between major and minor with the same accidentals.

Graphic illustration

We have created a graphic visualization of the circle of fifths. You can click on the graphic below to get a large version of the image.

Example

If you are playing a melody in D major and want to modulate to a related key, you can use the circle of fifths to find the closest ones: G major (one fifth down) or A major (one fifth up). These changes feel natural to the ear because the keys share many notes.