Circle of fifths

The notion of circle of fifths is born in 17^th century, I'm not a musicologist but I founded these information on the Internet:

1679: Nikolay Diletsky (music theorist and composer) introduce the notion or circle of fifths in his treatise Idea grammatikii musikiyskoy

1728: Johann David Heinichen (Deutch music theorist and composer) give a name to this concept of circle of fifths in hi treatise Der Generalbass in der Composition

Modern circle of fifths

Below is the modern circle of fifths: The interval between each Major key and each minor key is a perfect fifth:

Major key: C G D A E B (Or D♭) F♯ (or G♭) C♯ (or D♭) A♭ E♭ B♭ F
minor key: A E B F♯ C♯ A♭ (or G♯) E♭ (or D♯) B♭ (or A♯) F C G D



How to read this circle of fifths:

Inside the ring of the circle: minor key (in blue)
Outside the ring of the circle: Major key
On the ring: The numbers of accidentals for the Major key and their relative minor keys.

For example, G Major key and E minor key have only 1 sharp as key signature. The circle show thatG Major key and E minor key are relative keys.

Now we will see what we can do with this circle of fifths:

Finding key names and key signatures with the circle of fifths

With the circle of fifths, finding key names and key signatures is very easy: Imagine you want to know the key of F# minor, you had just to read the circle: the key signature of F# minor contains 3 sharps (3♯)




And if you want to know the name of the major key of the key signature that contains five flats (5♭), you just had to read the circle. The name of the minor key with a key signature composed by 5♭ is D flat Major.

Finding closely related keys with the circle of fifths

Finding closely related keys with the circle of fifths is very easy, they are next to each others, imagine you want to determine all closely related keys of C minor key, so you just had to read the circle of fifths:



Closely related keys of C minor key are:

- F minor
- G minor
- B flat Major
- E flat Major
- A flat Major