The circle of fifths is an almost magical tool for musicians!
Magical in its simplicity. Here is an ingenious invention to help you find major and minor key signatures, scales, chords and more.
Before we look at the picture of the Circle of 5ths (below), you first need to know what it is made up from.
Maybe it seems a bit confusing at first, but it is actually rather easy:
On the piano keyboard you can easily see them as:
A perfect fifth is the interval between two notes that are exactly 3 1/2 steps or tones apart.
(If you'd like to learn more about music theory, I recommend The Essentials of Music Theory. It's great for self study.)
Start from the lowest C on the keyboard (to the left). Play a perfect fifth up... G. Right.
Continue another perfect fifth... D.
You've got it!
Now continue like this and you will get: C-G-D-A-E-B-F#... What?!
-Why a black key?
Remember that between B and F there is a diminished fifth, only 3 steps, so we have to take F up 1/2 a step. OK?
Let's continue, where
were we? Here we go:
F#/Gb (the same key!)- C#/Db-(eh..let's call them "flats"(b) from now on) - Ab- Eb - Bb - back to the white keys now...
F - and...yes! We are back on C again!!
The clock has 12 hours. Neat! We can use the clock as a template! Start at 12 o'clock. Let's decide that C is here. Going to the right, around the clock and you will return to C again.
-Hey- wait a minute! I can't see any 8,9,10 or 11 sharps or flats?
Yeah, that would be unnecessary. Instead of having one circle with only sharp key signatures and another with only flats, which would then give us an awkward key signature with 11 sharps or flats at 11 o'clock...
...We use the fact that the black keys can have two names, and rename them after 7 sharps/flats. (There is a little overlap as you can see.)
So the circle of fifths you see here is "merged" with what could have been a circle with only sharps and a circle with only flats. One side is with sharps, and the other with flats. C is "natural" since it uses only white keys.
And finally, for all the music theory geeks like me- isn't the Circle of Fifths just beautiful?
My recommendation: You can learn more about music theory with Alfred's Essentials of Music Theory, perfect for beginners.