Lesson 16: The Circle of Fifths

There are twelve major keys and twelve minor keys, each with its own key signature — and the circle of fifths is the map that organises all twenty-four of them. It is a circular diagram, like a clock face, with C major at the top (no sharps or flats). Move one step clockwise and you reach G major, with one sharp. Each step clockwise adds one sharp, and each step takes you to the key whose tonic is a perfect fifth above the last: C, G, D, A, E, B, F sharp, C sharp. Move counterclockwise from C and you reach F major, with one flat; each step counterclockwise adds one flat: F, B flat, E flat, A flat, D flat, G flat, C flat.

The circle works because of how scales are built. The fifth note of the C major scale is G, so G major is the next key clockwise — and the fifth note of G major is D, the next key after that. At each step, exactly one note changes, so neighbouring keys on the circle are closely related: they share almost all their notes. Keys opposite each other on the circle, like C major and F sharp major, share almost nothing. This is why composers usually modulate to a neighbouring key: the move is smooth, because most of the notes stay the same.

Sharps, Flats and Relative Minors

The circle also shows the order in which sharps and flats are added. Sharps appear in the order F sharp, C sharp, G sharp, D sharp, A sharp, E sharp, B sharp; flats appear in the reverse order, B flat, E flat, A flat, D flat, G flat, C flat, F flat. The key signature of any key is simply the first few sharps or flats in that order: D major has two sharps, F sharp and C sharp; E flat major has three flats, B flat, E flat and A flat. Inside the circle sit the relative minor keys: A minor inside C major, E minor inside G major, D minor inside F major, and so on — each minor sharing its major neighbour's key signature. At the bottom of the circle, three keys meet in the same place: F sharp major and G flat major sound identical (they are enharmonic equivalents), and so do C sharp major and D flat major.

Using the Circle

Musicians use the circle every day. To find a key signature, count the steps from C. To find which chords belong in a key, look at the neighbours: the chords either side of any key on the circle are its IV and V chords, and its relative minor sits just inside. To choose a modulation, pick a neighbouring key. And to practise scales, work around the circle in order — each scale adds just one new sharp or flat, so the sequence is a natural ladder of difficulty. Once you can draw the circle from memory, you hold the whole system of keys in your head.

Using the Circle to Build Progressions

The circle of fifths is more than a memory aid for key signatures — it is a map of how chords relate. Take any key on the circle: the keys immediately to its left and right are its subdominant (IV) and dominant (V), the two chords it is most closely related to. In C major, F is one step counterclockwise and G is one step clockwise — exactly the IV and V chords. The relative minor sits just inside, and the keys two steps away are the next most useful. This is why the circle is a composer's tool: to write a progression, start at your key and walk around the circle, choosing neighbours for smooth moves and distant keys for dramatic ones. Jazz musicians use the circle constantly, because the most common jazz progression — ii–V–I — is a walk around the circle in fifths: in C major, D minor to G major to C major is three steps counterclockwise. Practising scales around the circle is the standard way to learn all twelve keys, because each new scale changes only one note from the last. If you can draw the circle from memory and play the scales around it, you have the whole key system at your fingertips.