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Theory · Reading Chord Symbols

The Chord
Symbol Decoder

What every symbol means — not what notes it spells.

Cm9

Root

The note the chord is built on.

Quality

Major, minor, diminished, augmented — or dominant by omission.

Extension

How far past the triad the stack reaches.

Read every symbol left to right in those three parts. Alterations, slashes and sus markings hang off the end — they modify the chord, they never replace the system.

Quality — what kind of chord

m · min · −

Minor

Three ways to write the same thing.

maj · Δ

Major 7th

Δ always carries the 7 — Δ and Δ7 mean the same chord.

dim · °

Diminished

The 5th is lowered. With a 7 (dim7, °7) it is fully diminished — a stack of minor 3rds.

Half-diminished

Identical to m7♭5. Written ø or ø7 — either way it is a 7th chord.

+ · aug

Augmented

The 5th is raised.

7 (no symbol)

Dominant

The absence of a quality symbol is the symbol. Nothing in front of the 7 means dominant.

Extensions — how far it stacks

Adds the 6th. It replaces the 7th rather than stacking on it — a 6 chord is not a 7th chord.

The 7th. Which 7th is decided by the quality to its left.

9 · 11 · 13

Reach past the 7th. Writing one implies the 7th underneath it.

add

add9 means the triad plus that note, with no 7th. The word add is what cancels the 7.

Alterations — one note moved

♭5 · ♯5

The 5th, lowered or raised.

♭9 · ♯9

The 9th, lowered or raised.

♯11

The 11th, raised.

♭13

The 13th, lowered.

♭5 and ♯11 sound alike but do different jobs. ♭5 moves the chord’s 5th; ♯11 sits above the 7th and leaves the 5th where it is. Same story for ♯5 and ♭13.

Slash chords

C/E

Chord on the left, bass note on the right — read it “C over E.” If the bass note belongs to the chord it is an inversion; if it does not, it is a new note underneath. Either way the chord itself is unchanged.

Sus chords

sus4 · sus2

The 3rd is replaced, not added — by the 4th, or by the 2nd. No 3rd means no major and no minor, which is why a sus chord sits unresolved. Most often met as 7sus4.

Altered

alt

An altered dominant. Every alteration is on the table — ♭9, ♯9, ♯11, ♭13 — and you pick. It is permission, not a fixed chord.

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The ChordSymbol Decoder

Root

Quality

Extension

The Chord
Symbol Decoder

The Chord Symbol Decoder