Question 1

What is the circle of fifths for?

Accepted Answer

It arranges the twelve keys so that neighbours are closely related — one step clockwise adds a sharp, one step anticlockwise adds a flat. That makes it a map for three jobs: remembering key signatures, finding chords that belong together, and choosing a key to modulate to, which is usually a neighbour.

Question 2

How do I read a key signature off it?

Accepted Answer

Count the steps clockwise from C: G has one sharp, D two, A three, and so on. Anticlockwise counts flats: F has one, Bb two, Eb three. The sharps always arrive in the order F C G D A E B, and the flats in the reverse order, B E A D G C F.

Question 3

What is the relative minor?

Accepted Answer

The minor key that shares a key signature with the major — A minor with C major, E minor with G major. It sits inside the circle, on the same wedge, and it starts on the sixth degree of the major scale. Same notes, different home.

Question 4

Why do F# and Db sit next to each other?

Accepted Answer

Because the circle closes: keep going clockwise and the sharps pile up until you reach the same pitches that the flat keys have been spelling differently. F# major and Gb major are the same six black-and-white keys written two ways. This chart shows the spelling musicians meet most often at each point.

Circle of fifths — press a key and hear it

C major · Am

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