Circle of Fifths — Keys, Chords & Key Signatures

The Circle of Fifths in The Ultimate Piano shows all 12 keys with their signatures, relative minors and diatonic chords. Select a key and its seven chords appear as coloured chips; one click plays the triad. A strength of this version is that it is not a static picture — the same wheel sets the key everywhere else in the app.

The circle of fifths arranges all 12 keys so each neighbor shares six of seven scale tones — the most practical map of Western tonal music.

On this page

Major Keys, Minor Keys & Key Signatures Selecting a Key Diatonic Chords Where the Circle of Fifths Appears Use Cases Frequently Asked Questions

Major Keys, Minor Keys & Key Signatures

The wheel displays three concentric rings covering all 12 notes of the chromatic scale:

Ring	Content
Outer ring	12 major keys (C, G, D, A, E, B, F#/Gb, Db, Ab, Eb, Bb, F)
Inner ring	12 relative minor keys (Am, Em, Bm, F#m, C#m, G#m, Ebm, Bbm, Fm, Cm, Gm, Dm)
Center segments	Key signatures — number of sharps or flats

Each key position uses a consistent color that also appears in chord displays throughout the app.

Selecting a Key

1. Click any segment on the wheel — the key highlights and its name appears on the Select button
2. The diatonic chord bar below the wheel updates immediately
3. Click Select to confirm, or Cancel to close without applying

Enharmonic keys — keys with two valid spellings (F♯/G♭, D♭/C♯, B/C♭) show both names inside the segment. Click the name you want to select that spelling. The active spelling appears bold; the alternative fades out. The key signature display updates to reflect the chosen spelling (e.g., 6 sharps vs. 6 flats).

Play preview: After selecting a key, a ▶ button appears in the center of the wheel. Click it to hear the triad of the selected key played with piano sound — major keys play a major triad (1–3–5), minor keys a minor triad (1–♭3–5).

Random key: Click the 🎲 button to spin to a random key — useful for rotating through all 12 keys in practice.

Diatonic Chords

When you click a key, the chord bar shows all 7 chords that belong to that key. Each chip displays:

Roman numeral (I, ii, iii, IV, V, vi, vii°) — the chord's scale-degree function
Chord name with correct enharmonic spelling (e.g., C♯ not D♭ in D major context)
Color matching the Circle of Fifths color system

Minor keys are interpreted as natural minor (Aeolian). For example, A natural minor: Am, B°, C, Dm, Em, F, G.

The diatonic chords of any key work naturally together — use them as a starting point for Chord Progressions.

Where the Circle of Fifths Appears

The wheel is integrated across the entire app:

The key button in the app header (showing e.g. "C / Am") opens the Circle of Fifths to set the global key for the session. This key determines which accidentals appear in the note names display and on the sheet music staff. Selecting a key here affects the whole app, not just one module.

The Circle of Fifths card in the Learn menu opens the wheel in pure exploration mode. No key is selected or applied anywhere — it's a tool for studying how keys, key signatures, and diatonic chords relate to each other.

Practice Modules

Module	What the CoF selects
Arpeggio Training	Root note and mode (major/minor) for the arpeggio exercise
Chord Progressions	Key for the progression exercise
Passing Chords	Key shown as a major/minor pair (e.g., C / Am)

Play & Create

Module	What the CoF selects
Leadsheet editor	Original key of the leadsheet — also available separately for the transposed key
Diagram Generator	Tonal center for roman-numeral chord input

Use Cases

Understand key relationships — neighbors on the circle share the most notes
Set accidentals for note display — select the key in the header to control which sharps or flats appear
Practice across all 12 keys — use the random spin for systematic rotation
Build chord progressions — click a key, see its 7 chords immediately
Navigate major/minor — every major key sits directly above its relative minor

Frequently Asked Questions

What is the Circle of Fifths and why is it useful?

12 keys, arranged so that each neighbor is a perfect fifth apart and shares six of seven scale notes — that is the Circle of Fifths. It is the standard reference for understanding key relationships, choosing chords that work together, and navigating between keys in music.

How do I use the Circle of Fifths to find diatonic chords in a key?

7 chords appear in the chord bar the moment you click a key on the wheel. These are the scale's diatonic chords — labeled I through vii° with their quality (major, minor, diminished). Any combination of these chords will sound harmonically coherent in that key.

What is the difference between major and minor keys on the Circle of Fifths?

12 major keys sit on the outer ring; their 12 relative minors share the same key signatures on the inner ring. C major and A minor both have no sharps or flats and occupy the same slice. Minor keys in this app use natural minor (Aeolian) as the reference scale.

What are key signatures and how does the Circle of Fifths display them?

0 to 7 sharps or flats define every key signature, and the Circle of Fifths shows this count in the center of each wheel slice. C major uses none; G major uses one sharp (F♯); F major uses one flat (B♭). Because the count sits right on the slice, you can read a key's key signature without knowing the key by name.

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