Circle of Fifths

The circle of fifths is a handy tool for organizing the 12 possible Major scales into what is called Key Signatures.

The "key" refers to the starting note (root) of the scale. "Key signature" simply refers to the number of sharps or flats that occur in each key. No two major scales will contain the same number of sharps or flats, so scales can be easily organized by key signature.

If you build a Major scale from the 5th note of another Major scale, the new scale will have one more sharp than the scale you started with. That's where the "5ths" in the circle of 5ths comes from, but what about the "circle" part? The circle comes from the fact that if you continue to build a scale from the 5th note of the previous scale, you will eventually wind up right back at the beginning, C Major:

G is the 5th note of C Major.
D is the 5th note of G Major.
A is the 5th note of D Major.
E is the 5th note of A Major.
B is the 5th note of E Major.
F# is the 5th note of B Major.
C# is the 5th note of F# Major.
G# is the 5th note of C# Major.
D# is the 5th note of G# Major.
A# is the 5th note of D# Major.
F is the 5th note of A# Major.
C is the 5th note of F Major.

We're right back where we started, as if we traveled in a circle.

Here's a handy sing-song for remembering which notes are sharp or flat in each key:

Sharps = Father Charles Goes Down And Ends Battle.

Flats = Battle Ends And Down Goes Charles' Father.

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0 flats or sharps = Key of C

1 sharp "F#" = Key of G

2 sharps "F#, C#" = Key of D

3 sharps "F#, C#, G#" = Key of A

4 sharps "F#, C#, G#, D#" = Key of E

5 sharps "F#, C#, G#, D#, A#" = Key of B

6 sharps or flats "F#, C#, G#, D#, A#, E#" or "Bb, Eb, Ab, Db, Gb, Cb" = F# or Gb (same thing)

5 flats "Bb, Eb, Ab, Db, Gb," = Key of Db

4 flats "Bb, Eb, Ab, Db" = Key of Ab

3 flats "Bb, Eb, Ab" = Key of Eb

2 flats "Bb, Eb" = Key of Bb

1 flat "Bb" = Key of F

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Thanks to Kyle H. & vwodwo22 for this COF