Circle of Fifths & Key Identification
See how all 12 keys connect on the Circle of Fifths, learn relative minor keys, and master quick tricks to identify any key signature.
The Circle of Fifths
The Circle of Fifths is a visual map of all 12 major and minor keys, showing how they relate to each other. Moving clockwise adds sharps; moving counter-clockwise adds flats.
Circle of Fifths Diagram
How to read it: Start at C (top, no sharps or flats). Each step clockwise goes up a fifth and adds one sharp. Each step counter-clockwise goes up a fourth and adds one flat. The inner ring shows the relative minor key for each major key.
Relative Minor Keys
Every major key has a relative minor that shares the same key signature. The relative minor starts on the 6th degree of the major scale — or three half steps below the major key's root.
Complete Key Signature Reference
| Accidentals | Major Key | Relative Minor | Sharps / Flats |
|---|---|---|---|
| — | C major | A minor | none |
| ♯ | G major | E minor | F♯ |
| ♯♯ | D major | B minor | F♯ C♯ |
| ♯♯♯ | A major | F♯ minor | F♯ C♯ G♯ |
| ♯♯♯♯ | E major | C♯ minor | F♯ C♯ G♯ D♯ |
| ♯♯♯♯♯ | B major | G♯ minor | F♯ C♯ G♯ D♯ A♯ |
| ♯♯♯♯♯♯ | F♯ major | D♯ minor | F♯ C♯ G♯ D♯ A♯ E♯ |
| ♯♯♯♯♯♯♯ | C♯ major | A♯ minor | all 7 sharps |
| ♭ | F major | D minor | B♭ |
| ♭♭ | B♭ major | G minor | B♭ E♭ |
| ♭♭♭ | E♭ major | C minor | B♭ E♭ A♭ |
| ♭♭♭♭ | A♭ major | F minor | B♭ E♭ A♭ D♭ |
| ♭♭♭♭♭ | D♭ major | B♭ minor | B♭ E♭ A♭ D♭ G♭ |
| ♭♭♭♭♭♭ | G♭ major | E♭ minor | B♭ E♭ A♭ D♭ G♭ C♭ |
| ♭♭♭♭♭♭♭ | C♭ major | A♭ minor | all 7 flats |
Finding the relative minor: Count three half steps (a minor third) down from the major key. C major → A minor. G major → E minor. D major → B minor. They share the same key signature but have a different tonal center.
How to Identify a Key Signature
Follow these simple rules to quickly determine the key of any piece you encounter.
Step-by-Step Identification
Step 1: Find the last sharp in the key signature.
Step 2: Go up one half step from that sharp.
Step 3: That's your major key!
Example: Last sharp = G♯ → up one half step = A → A major
Step 1: Find the second-to-last flat.
Step 2: That flat is the name of the key!
Step 3: (One flat = F major, memorize this.)
Example: Flats = B♭ E♭ A♭ → second-to-last = E♭ → E♭ major
Major or Minor?
A key signature alone doesn't tell you if the piece is major or minor — you need to listen or look at the music. Here are some clues to help:
The piece tends to start and end on the note named by the major key. The overall mood often sounds bright and resolved.
The piece tends to start and end on the note three half steps below the major key. Look for raised 6th and 7th degrees (accidentals in the music).
No sharps or flats? The key is either C major or A minor. Look at the first and last notes, the lowest note in the bass, and the overall feel to decide which one.