Circle of Fifths (its super cool)

Ever wonder why key signatures are in a seemingly strange pattern? (I mean, why can't they just go in alphabetical order, right?) Well there's actually a very methodical explanation and it's what we music lovers refer to as The Circle of Fifths!

Before we jump right in - let's define  - a "fifth". It is often referred to as a perfect fifth and its extremely pleasing to the ear (think "do - sol - do" if you're into solfege or I - V - I if you're into chords). Pitches that are a perfect fifth apart, have frequencies in a ratio of 3:2 and are 7 semitones apart, based on a diatonic (12 tone) scale.

However, in it's simplest terms - just count the letters:

So, if you start with C major (with no sharps or flats in it's key signature) then go up by 5 letters including C (hold out your fingers and count thumb C, pointer D, middle E, ring F, pinky G. 

G is one fifth above C. 

You can do the same thing then starting on G and find the D is one fifth above D. 

C D E F G

1  2  3  4  5

G A B C D 

1 2  3  4  5 

And guess what it works all the way around the circle!!!

**If you're using the strictly letter system to understand the circle of fifths - make sure to check the accidentals (sharps and flats) in your key signature. For example, if you're looking at B major (5 sharps) and you go up a fifth - if you just use letters you might think the next key is F major - but you have to check the key signature! You've already sharped the F, therefore the next key is F# sharp major. 

 

Now you might be looking at that circle and say - now what the heck is going on with those sharps and flats?? They aren't following the same pattern. But in fact - THEY ARE. 

Let's take G major for example (the dark orange block in the wheel). It has one sharp in it - which is F#. (Another blog post to come on why certain keys have certain accidentals...) 

But, the key of G major has an F#, and the next key of D major has TWO sharps - F# and C# which are indeed A FIFTH APART. 

Thus continues our circle of fifths!

Now, if you were to go counter clockwise on the circle - you're now going DOWN by a fifth. But, let's just conquer one direction at a time.