Four piano chord formulas, and the pages that keep them apart

Weiwei Yang — Wed, 30 Sep 2026 03:22:48 +0000

I build PianoGrid, a free browser piano reference. This note is about how the chord pages separate formulas. It is a reference, not a course, and the chord diagrams mark pitches rather than finger numbers.

A chord symbol is a root plus a formula. The same letter can name different chords when the formula changes.

Major triads

A major triad is a root, a major third and a perfect fifth: 1–3–5. In root position the third and fifth sit four and seven semitones above the root. C major is C–E–G.

The major piano chords page lists all 12 roots. Each card shows the written spelling and a keyboard diagram. Open a chord to compare inversions. Octave numbers describe register. They are not finger numbers.

Minor triads

A minor triad uses 1–♭3–5: a root, a minor third and a perfect fifth. Compared with the parallel major triad, the third is one semitone lower. The minor piano chords chart lists the 12 roots with that formula.

These four detail pages spell the notes and show root position plus two inversions. The diagrams show note positions, not a prescribed hand shape. Changing the inversion changes the lowest note. It does not change the chord root. The slash symbol names the written bass note.

B minor is B, D, F♯. The page's root position is B3–D4–F♯4.
E minor is E, G, B. Root position there is E4–G4–B4.
G minor is G, B♭, D. Root position there is G3–B♭3–D4.
D minor is D, F, A. Root position there is D4–F4–A4.

Diminished triads

A diminished triad is a root, a minor third and a diminished fifth: 1–♭3–♭5. C diminished is C–E♭–G♭. The diminished chords chart keeps the written spelling even when two names share a piano key. Each detail page keeps the same three chord tones across root position, first inversion and second inversion.

Seventh chords

A seventh chord adds a fourth tone above a triad, so it has root position and three inversions. The seventh piano chords page separates four families:

dominant seventh: 1–3–5–♭7
major seventh: 1–3–5–7
minor seventh: 1–♭3–5–♭7
half-diminished seventh: 1–♭3–♭5–♭7

A7 is the dominant-seventh example A, C♯, E, G. On that page, root position is A3–C♯4–E4–G4. The inversions are A7/C♯, A7/E and A7/G. Finger numbers are not included.

Where to start