If you’re looking for a musical New Year’s resolution to make, learning the circle of fifths is a great goal. Relationships between notes are at the heart of what makes music “work,” and the circle of fifths is a visual diagram that arranges the 12 pitches and keys so that it’s easy to begin to recognize those relationships.
A fifth is an interval five note-names apart, counting both the starting and ending pitches. For example, count the five note-names “C D E F G” to find that C to G is a fifth. In the circle of fifths, we deal more specifically with perfect fifths, meaning intervals made up of exactly seven half steps, or steps on the piano keys. To create the circle of fifths, start at the top of the circle with C. Move clockwise and add pitches (at the same positions as a clock) in the order of ascending perfect fifths, until all 12 pitches are represented and you return to C.
For the bottom three positions of the circle, include both enharmonic spellings of the pitch (B and Cb, F# and Gb, and Db and C#). For the remaining positions in the left half of the circle, use flat spellings.
You’ll notice that all major key signatures are represented on the circle. Plus, we can now easily find the number of sharps and flats in each key signature. For sharp key signatures, start at the top of the circle with C major (no sharps). As you move clockwise, add one sharp at each position on the circle: The key of G major has one sharp, D major has two sharps, and so on. For flat key signatures, also start with C major (no flats) and move counter-clockwise. Add one flat at each position: F major has one flat, Bb major has two flats, and so on.
Interestingly, the order of sharps in any key signature follows a pattern of ascending fifths: F#, C#, G#, D#, A#, E#, B#. For instance, in the key of B major, which has five sharps, the sharps are F#, C#, D#, G#, and A#. The order of flats follows a pattern of descending fifths: Bb, Eb, Ab, Db, Gb, Cb, Fb.
What else can the circle of fifths tell us? When key changes or modulations happen in music, it is most likely that the key will move to an adjacent one on the circle of fifths. That’s because adjacent keys are very similar to each other and will allow for a smooth, musical transition. The same idea applies to chord progressions. An A-major chord, for example, has a strong pull toward an E-major or D-major chord. (Of course, we can’t strictly follow this rule—if we did, there would be no surprises in music!)
With an understanding of the circle of fifths, you have a solid foundation on which to build your music theory knowledge in the coming year.