Harmonic field: the chords of every key

The harmonic field is the set of chords a scale produces when you stack thirds on each of its degrees. Understanding a key is not memorizing chord lists: it is seeing how degrees, chords and functions connect — and where they fall on the fretboard.

In C major, the collection C–D–E–F–G–A–B yields a triad (a three-note chord) and a seventh chord (the same chord plus its seventh, a fourth note) on every degree; the qualities (major, minor, half-diminished) follow from the real intervals between the collection’s notes. The most practical functional reading gives these chords three roles: tonic (I, vi and sometimes iii) stabilizes; subdominant (ii and IV) prepares; dominant (V and vii°) builds the tension that asks to resolve. These are tendencies of use, not absolute rules.

Tonic chords stabilize and rest; subdominant chords prepare motion; dominant chords build the tension that asks for resolution.

Example: C major

Degree	Triad	Seventh	Function
I	`CCCC`	`Cmaj7Cmaj7Cmaj7Cmaj7`	tonic
ii	`DmDmDmDm`	`Dm7Dm7Dm7Dm7`	subdominant
iii	`EmEmEmEm`	`Em7Em7Em7Em7`	tonic
IV	`FFFF`	`Fmaj7Fmaj7Fmaj7Fmaj7`	subdominant
V	`GGGG`	`G7G7G7G7`	dominant
vi	`AmAmAmAm`	`Am7Am7Am7Am7`	tonic
vii°	`B°`	`Bm7b5`	dominant

Example: A minor

Degree	Triad	Seventh	Function
i	`AmAmAmAm`	`Am7Am7Am7Am7`	tonic
ii°	`B°`	`Bm7b5`	subdominant
III	`CCCC`	`Cmaj7Cmaj7Cmaj7Cmaj7`	tonic
iv	`DmDmDmDm`	`Dm7Dm7Dm7Dm7`	subdominant
v	`EmEmEmEm`	`Em7Em7Em7Em7`	dominant
VI	`FFFF`	`Fmaj7Fmaj7Fmaj7Fmaj7`	subdominant
VII	`GGGG`	`G7G7G7G7`	subdominant

This is the natural-minor field. In practice the v often becomes V (major) or V7 — borrowed from the harmonic minor — to create the leading tone that pulls back to the tonic.

All 24 keys, around the circle of fifths

Major keys

C major G major D major A major E major B major F# major Db major Ab major Eb major Bb major F major

Minor keys

A minor E minor B minor F# minor C# minor G# minor Eb minor Bb minor F minor C minor G minor D minor

In Chord and Fret, the Circle of Fifths screen shows any key’s harmonic field with audio and fretboard positions — triads, sevenths and the secondary dominants. Open in Chord and Fret →

Frequently asked questions

What is the harmonic field of a key?

It is the set of chords built by stacking diatonic thirds on each degree of the key’s scale. In C major: C, Dm Dm Dm Dm, Em Em Em Em, F, G, Am and B° (triads) — or Cmaj7 Cmaj7 Cmaj7 Cmaj7, Dm7 Dm7 Dm7 Dm7, Em7 Em7 Em7 Em7, Fmaj7 Fmaj7 Fmaj7 Fmaj7, G7 G7 G7 G7, Am7 Am7 Am7 Am7 and Bm7(b5) (sevenths).

How do the major and minor fields differ?

The major field comes from the major scale; the minor one from the natural minor. In practice a minor key mixes materials: the v often becomes V or V7 (from the harmonic minor) to create the leading tone — the note a half step below the tonic that pulls back home.

What do tonic, subdominant and dominant mean?

They are the three practical functions: tonic chords stabilize or rest; subdominant chords prepare motion; dominant chords hold the tension that tends to resolve to the tonic.

Do I need to memorize all 24 fields?

No. Master C major and A minor as your reference axis — degrees and functions are the same in every key; only the notes change. Transposing beats memorizing.

Updated August 5, 2026