Chord Construction

What this section teaches

A chord is defined by the distances between its notes, not by any instrument or shape. Stack a major third and a minor third and you have a major triad — from any root, in any register, on any instrument, sung by any three voices. Every one of the 62 chord qualities documented here is such a recipe: a formula of intervals above a root. The families tell the story of harmony's growing vocabulary — triads, the sevenths that give chords direction, suspensions that trade the third for ambiguity, sixths and ninths that add color without changing function, and the extended and altered qualities that give jazz its glow. A chord symbol like Cmaj7 or G7#9 is just one of these formulas with a root attached; this section is where the symbols become legible.

How to use these pages

Pick a root to see all 62 qualities built on it, or go straight to a chord's page for its formula, exact notes, family, and the keys and scales that contain it. Reading a chart, look up the symbols you don't recognize; writing, browse a family for the color you're missing — the difference between add9 and 9, or 7sus4 and plain 7, is exactly one note, and the pages make the note visible.

Where to go next

Chord formulas are stacked intervals; keys assign the chords their jobs in keys; and the functional harmony guide explains why those jobs make progressions move.