Chord symbols

Lead sheets, songbooks and most popular music write chords as symbols rather than notation. The system is compact and, once you see the structure, entirely regular.

The structure

Every symbol is a root, then a quality, then any extensions, then any alterations, then optionally a bass note.

C     maj7     ♯11     /E
root  quality  alter   bass

Quality suffixes

The single most common misreading: C7 is a dominant seventh with a flattened seventh. The major seventh needs the word: Cmaj7.

Extensions

Numbers above 7 refer to compound intervals — 9 is a second an octave up, 11 a fourth, 13 a sixth.

An extension implies the seventh below it. C9 means C E G B♭ D, not C E G D. If you want the ninth without the seventh, write Cadd9.

Alterations

A sharp or flat before an extension number raises or lowers that note: C7♭9, C7♯11, C7♯5. These are the standard vocabulary of altered dominant chords in jazz.

Slash chords

A slash names the bass note: C/E is a C major chord with E in the bass — the first inversion.

The bass note does not have to belong to the chord. C/B♭ is a common way to write a bass line moving under a static harmony.

What symbols deliberately leave out

A chord symbol specifies which notes, not how to arrange them. It does not say:

• which octave anything is in
• how many times a note is doubled
• what order the notes go in above the bass
• what rhythm to play

That is the point. A symbol is an instruction to a player who is expected to voice it themselves, which is why the same lead sheet sounds different in different hands. Notated music makes those choices for you; a chord symbol delegates them.