Circle of Keys (also known as Circle of Fifths)

The complete Circle of Keys:  C-G-D-A-E-B-Gb-Db-Ab-Eb-Bb-F-C

Upon initially looking at the Circle of Keys one may wonder "why" or "how".  It's actually quite easy once you understand the basic Major Scale theory and Tetrachord Theory.

Basically, a major scale consists of 2 tetrachords with the interval of a whole tone or step between them. (as reviewed in Major Scale theory).

The second, or upper tetrachord of any ascending major scale becomes the first, or lower tetrachord of a new major scale whose name is derived from the first note, or tone of that tetrachord.

Therefore, the fifth note, or tone of any ascending major scale (which is the first note of the second tetrachord) is the beginning of a new major scale.

The scale starting a fifth above C is the G major scale with 1 sharp.
The scale starting a fifth above  G is the D major scale with 2 sharps.
The scale starting a fifth above  D is the A major scale with 3 sharps.
The scale starting a fifth above  A is the E major scale with 4 sharps.
The scale starting a fifth above  E is the B major scale with 5 sharps.
The scale starting a fifth above  B is the F# major scale with 6 sharps.
The scale starting a fifth above  F# is the C# major scale with 7 sharps.

Notice how the sharps ascend up the staff, and how the flats descend down the staff. This is important in understanding the circle of keys.

The second, or lower tetrachord of any descending major scale becomes the first, or upper tetrachord of a new major scale whose name is derived from the first note, or tone of that tetrachord.

The scale starting a fifth below C is the F major scale with 1 flat.
The scale starting a fifth below F is the Bb major scale with 2 flats.
The scale starting a fifth below Bb is the Eb major scale with 3 flats.
The scale starting a fifth below Eb is the Ab major scale with 4 flats.
The scale starting a fifth below Ab is the Db major scale with 5 flats.
The scale starting a fifth below Db is the Gb major scale with 6 flats.
The scale starting a fifth below Gb is the Cb major scale with 7 flats.

Notice how the sharps ascend up the staff, and how the flats descend down the staff. This is important in understanding the circle of keys.

 

For questions or comments about these Theory pages please contact Steve at stevesklar@gmail.com

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