Circle of Fifths Reference
Major / relative-minor keys with their sharps and flats.
Overview
The circle of fifths reference is a quick lookup for every major and relative-minor key paired with its key signature — how many sharps or flats it carries and which notes those are. Pick a key and the tool returns the full diatonic scale, the relative minor, the parallel minor, and the sharps or flats that belong in the staff signature.
It's a foundation tool for composers planning modulations, transcribers identifying the key of a piece by counting accidentals, and students memorising key signatures. The circle also makes harmonic relationships visible at a glance: keys that sit close together share most of their notes and modulate smoothly, while keys on opposite sides of the wheel feel like dramatic shifts.
How it works
Start at C major (no sharps or flats) and move clockwise by a perfect fifth: G major (1 sharp, F#), D major (2 sharps, F# C#), A major (3 sharps), and so on through C#/Db major at the bottom. Counter-clockwise moves by a perfect fourth (or a fifth down), giving F major (1 flat, Bb), Bb major (2 flats), Eb major (3 flats), and so on.
Each major key has a relative minor that shares its key signature, sitting a minor third below: A minor shares C major's signature, E minor shares G major's, and so on. The order of sharps and flats themselves follows the circle: F# C# G# D# A# E# B# for sharps, Bb Eb Ab Db Gb Cb Fb for flats, each step a fifth from the last. This system grows directly out of 12-tone equal temperament and the harmonic series.
Examples
G major → 1 sharp (F#), relative minor: E minor
Eb major → 3 flats (Bb Eb Ab), relative minor: C minor
F# major → 6 sharps (F# C# G# D# A# E#), relative minor: D# minor
A minor → No sharps or flats (relative to C major)
FAQ
Why are there enharmonic equivalents like F# major and Gb major?
They contain the same pitches but spell them differently. F# uses six sharps; Gb uses six flats. Composers pick whichever spelling makes the surrounding music easier to read.
What's the difference between relative and parallel minor?
The relative minor shares the same key signature (A minor and C major both have no accidentals). The parallel minor shares the same tonic but flips three notes (C major and C minor share the note C but differ in their third, sixth, and seventh).
How do I tell what key a piece is in?
Count the sharps or flats in the key signature, then decide between major and its relative minor by looking at the opening and closing chord and which note feels like home.
Does this work for modes too?
Yes. The modes (Ionian, Dorian, Phrygian, etc.) all derive from a major scale, so they share its key signature and can be located on the wheel by their parent major.
Why the perfect fifth specifically?
The fifth is the most consonant interval after the octave. Moving by fifths changes only one note at a time in the key signature, which is the smoothest possible step between keys.