Guide
The circle of fifths, explained
The circle of fifths is a map of how the twelve keys relate to each other. Step clockwise and you add a sharp; step anticlockwise and you add a flat. Keys that sit next to each other on the circle share six of their seven notes, which is why moving between neighbours sounds smooth and jumping across the circle sounds like a lurch.
How to read it
Start at C at twelve o’clock: no sharps or flats. Every clockwise step is a perfect fifth up and adds one sharp, so G has 1 sharp, D has 2 sharps, A has 3 sharps, and so on. Going anticlockwise is a fifth down — a fourth up — and adds flats instead: F has 1 flat, B♭ has 2 flats, E♭ has 3 flats.
At the bottom of the circle the two directions meet, and the same pitches get written two ways. That is why F♯ major and F♯ / G♭ are the same sounds on the keyboard spelled by different rules — the sharp side keeps sharpening, the flat side keeps flattening, and somewhere around six accidentals it stops mattering which name you use.
The three chords next door
A key’s two neighbours on the circle are its IV (one step anticlockwise) and its V (one step clockwise). Those three — I, IV and V — are the backbone of most songs ever written, and the circle puts them physically next to each other. The relative minor sitting on the inner ring is the vi, which is the fourth chord in the pop progression everyone already knows by ear.
Relative minors
Each major key shares its key signature with the minor key three semitones below it: the same seven notes, a different note treated as home. C major and A minor are the same white keys; what changes is where the music rests. The inner ring above pairs each one up.
Every key and its chords
The seven chords below are just the notes of the key stacked in thirds. Their qualities follow the same pattern in every key — major, minor, minor, major, major, minor, diminished — which is what makes a progression written in one key transposable into any other.
| Key | Signature | Relative minor | I | ii | iii | IV | V | vi | vii |
|---|---|---|---|---|---|---|---|---|---|
| C major | no sharps or flats | A minor | C | Dm | Em | F | G | Am | Bdim |
| G major | 1 sharp | E minor | G | Am | Bm | C | D | Em | F♯dim |
| D major | 2 sharps | B minor | D | Em | F♯m | G | A | Bm | C♯dim |
| A major | 3 sharps | F♯ minor | A | Bm | C♯m | D | E | F♯m | G♯dim |
| E major | 4 sharps | C♯ minor | E | F♯m | G♯m | A | B | C♯m | D♯dim |
| B major | 5 sharps | G♯ minor | B | C♯m | D♯m | E | F♯ | G♯m | A♯dim |
| F♯ major | 6 sharps | D♯ minor | F♯ | G♯m | A♯m | B | C♯ | D♯m | E♯dim |
| D♭ major | 5 flats | B♭ minor | D♭ | E♭m | Fm | G♭ | A♭ | B♭m | Cdim |
| A♭ major | 4 flats | F minor | A♭ | B♭m | Cm | D♭ | E♭ | Fm | Gdim |
| E♭ major | 3 flats | C minor | E♭ | Fm | Gm | A♭ | B♭ | Cm | Ddim |
| B♭ major | 2 flats | G minor | B♭ | Cm | Dm | E♭ | F | Gm | Adim |
| F major | 1 flat | D minor | F | Gm | Am | B♭ | C | Dm | Edim |
Hear it instead of reading it
A chart tells you which chords belong together. It cannot tell you what the pull between them feels like — the reason a V wants to fall home and a IV wants to lean. The trainer draws this same circle and lights it up from your microphone as you play, so the theory arrives attached to a sound you just made rather than as a diagram to memorise.
Open the circle in the trainer
Runs in the browser. Nothing to install.