Circle of Fifths: Music Theory

Every key fits in one circle. Turn it and you can see why G major has one sharp, D major two and E flat major three flats: each step to the right adds one. What a textbook shows as a table to memorise is a gesture here.

Tap any sector and you get the full key signature — how many accidentals and which ones, in order — its relative key and, when there is one, the enharmonic way of writing it. No setup, no menus: C major is already on top when you open the app.

WHAT YOU GET
◆ The wheel of the 12 keys with two rings: majors outside, minors inside.
◆ The key signature of each one: how many sharps or flats, and the order they appear in.
◆ The relative key, the one that shares the same signature.
◆ Enharmonics: F sharp major and G flat major sound alike and are written differently. Both are here.
◆ All 30 keys, not 24. Enharmonic spellings count separately, because on paper they are not the same thing.
◆ Works offline. No account, no sign-up.

DO-RE-MI, C-D-E OR THE GERMAN SYSTEM
A Spanish musician says "mi bemol" and an English one says "E flat". In Germany, B natural is called H and B is B flat. Pick your notation in Settings and the whole app changes, accidentals included. Most circle-of-fifths apps only speak one of these.

WHO IT IS FOR
For anyone studying harmony who keeps getting stuck on key signatures. For players who learned by ear and want to know why those three chords belong together. For the guitarist who has heard of the circle of fifths and never had it explained.

WHAT IT IS NOT
Not a tuner, not a metronome, not a course. It is the wheel, done properly, with the information you actually need while looking at it. A reference tool for studying key signatures; it does not replace a teacher.