Erasmus

Circle of fifths

The circle of fifths with a window on it. Turn the window to any key, by dragging it or tapping a key, and it frames that key's seven chords: I, IV and V across the top, their relative minors underneath. The window stays the same shape in every key: that's what transposing is.

Sound Clockwise = up a fifth. Each step adds a sharp.

Circle of fifths

C major Am C Am 0G major Em G Em 1♯D major Bm D Bm 2♯A major F♯m A F♯m 3♯E major C♯m E C♯m 4♯B major / C♭ major G♯m / A♭m B C♭ G♯m A♭m 5♯ 7♭F♯ major / G♭ major D♯m / E♭m F♯ G♭ D♯m E♭m 6♯ 6♭D♭ major / C♯ major B♭m / A♯m D♭ C♯ B♭m A♯m 5♭ 7♯A♭ major Fm A♭ Fm 4♭E♭ major Cm E♭ Cm 3♭B♭ major Gm B♭ Gm 2♭F major Dm F Dm 1♭ I IV V vii° The seventh chord of the key: this slot says minor, but in the key it is diminished (vii°) C major no sharps or flats
your key its relative minor the window: I · IV · V over vi · ii · iii dashed: the vii° slot — the wheel says minor, but in the key it's diminished (B° in C) shared with the key you're hovering

C major

no sharps or flats · relative minor: A minor

In the window

The three majors sit side by side on the circle; each minor sits under its relative major. A chord's swap shares two of its three notes, so it can stand in: vi for I, ii for IV, iii for V.

Hear I – IV – V – I Hear the scale

Changing key

Hover (or tap and hold) another key on the wheel to see which chords it shares with C major. Neighbors share four; the key across the circle shares none.

Remember the signatures

Sharps are added in this order: F C G D A E B — Father Charles Goes Down And Ends Battle.
Flats in the reverse order: B E A D G C F — Battle Ends And Down Goes Charles's Father.

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