Click a segment, or use the arrow keys. Right goes up a fifth, left goes down.

Chosen key

C major · Am relative

No accidentals in the key signature.

Diatonic chords

IC
iiDm
iiiEm
IVF
VG
viAm
vii°B°

Neighbours on the circle are neighbours in music: G clockwise, F anticlockwise. These are the keys a piece moves to without anyone noticing.

Open in Music paper Generate a progression in this key

Accidentals are always drawn in the same order and always at the same height: sharps F C G D A E B, flats the other way round. That is how a key signature is recognised at a glance.

Major keys with their relative minors, and the diatonic chords of the major. Modes and harmonic minor are another page.

How it works

In the Circle view, click a segment or use the arrow keys to turn the wheel.
Below you get the key signature drawn on the stave and the seven diatonic chords.
In the Modulations view the key sits at the centre, with the four doors out of it around.
The links take you to Music paper with the key already set.

What it does

It has two views. The circle shows the twelve major keys on the outer ring and their relative minors on the inner one; pick a key and it gives the key signature drawn on the stave, the seven diatonic chords with their symbols, and the degrees.

Modulations answers a different question: not where a key sits, but how you leave it. The key goes at the centre, its chords around it, and the four keys you can move to on the outside. Click a door and the map recentres; the path stays written underneath.

The four doors

There are four because these are the ones you walk through without the listener noticing they have entered another room: the dominant a fifth above, the subdominant a fifth below, the relative which shares the key signature, the parallel which shares the tonic.

From a minor key they are the same read in a mirror: dominant and subdominant stay in the mode you started from, while relative and parallel are the two ways of changing mode — the first keeping the key signature, the second keeping the tonic.

Pivot chords

A pivot is a chord that belongs to both keys: you play it meaning the first one and leave it meaning the second. From C to G there are four — C, E minor, G and A minor — and each changes name on the way across: the I becomes IV, the V becomes I.

No pivots is an answer, not a defect. C major and C minor share not one chord, and that is exactly why you hear that one happen: you arrive by the tonic, not by a shared chord.

There are six chords on the map, not seven. The seventh degree is diminished, and a diminished chord is not a door: it asks to resolve immediately, so it cannot hold the ambiguous moment a modulation leans on.

Secondary dominants

Behind a checkbox, because they are a second layer and not everyone is looking for them. A secondary dominant is the seventh chord built a fifth above a degree, and it pulls towards that degree the way the dominant pulls towards the tonic: in C, A7 leads to D minor and D7 leads to G.

Its root is already a note of the key. What is borrowed is the third, and that is the note that makes you hear the change of direction.

Why it is a circle

Because neighbours on the drawing are neighbours in music. Each step clockwise goes up a fifth and adds an accidental; the two keys either side of the one you picked, plus its relative minor, are the ones a piece moves to without anyone noticing.

A table of key signatures ordered by number of accidentals would say the same things without saying that one.

About the key signature

Accidentals are always drawn in the same order — sharps F C G D A E B, flats the other way round — and always at the same height on the stave. That is how a key signature is recognised at a glance, and a drawing that moves them reads as wrong even to someone who could not say why.

The order is not a graphic convention: it is the circle itself. Each fifth up adds one sharp, and the new sharp is always a fifth above the previous one.

About relative minors

Every major key shares its signature with a minor one, three semitones below. C major and A minor both have no accidentals; G major and E minor both have one sharp.

They are the same collection of notes read from two different starting points, which is why they sit on the same segment.

About the enharmonic

Only one segment has one: F♯ major with six sharps, or G♭ major with six flats. They are the same pitch written two ways, and the checkbox switches the spelling.

The other two classic pairs — C♯/D♭ and B/C♭ — have seven accidentals on one side and five on the other, so here they appear with the spelling people actually use. Showing all three would mean fifteen segments saying twelve pitches.

About note names

In Italian they are Do Re Mi. This is solfège, and that is how someone reading music in Italian reads it.

It is the opposite of what “Note to frequency” does, where the names stay C, D, E: that one is about a plugin keyboard, and nobody has ever seen “do” written on a plugin.

What is not here

Major and natural minor keys. The circle draws the twelve majors with their relatives; the map can also sit on a minor, and that minor is the natural one.

Harmonic minor is not here, and not by oversight: it would raise the seventh degree, turn the v into a V and change the list of pivots. A pivot that exists only if the player chooses the harmonic form is not a pivot, it is a guess — the map states what the key signature guarantees. Modes and melodic minor are another page.

The links go to Music paper with the key already set: one opens the stave, the other generates a chord progression in that key. From the map they carry the key you are on now, mode included, so a passage found here carries on over there.

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Circle of fifths