3. Chord Symbols Cheat Sheet

Every chord name is a root note followed by a quality — a short set of instructions describing how to alter a plain major triad. Learn what each suffix does and you can work out a chord you have never seen before from its name alone, instead of memorising shapes one at a time.

The starting point

A major triad is the 1st, 3rd, and 5th notes of the major scale built on the root. For C that is C, E, and G. Everything below is described as a change to those three notes.

The suffixes

m — minor. Flatten the 3rd. C–E–G becomes C–Eb–G.
7 — dominant 7th. Add the flattened 7th: C–E–G–Bb. This is the bluesy, unresolved one.
maj7 — major 7th. Add the natural 7th: C–E–G–B. Soft and floating, not bluesy at all.
m7 — minor 7th. Both changes at once: C–Eb–G–Bb.
sus2 / sus4 — suspended. Replace the 3rd with the 2nd or the 4th. With no 3rd the chord is neither major nor minor, which is why sus chords sound unfinished and want to resolve.
dim — diminished. Flatten both the 3rd and the 5th: C–Eb–Gb.
dim7 — diminished 7th. Add a doubly flattened 7th on top: C–Eb–Gb–A. Every note is three frets apart, which is why the same shape names four different chords.
aug — augmented. Sharpen the 5th: C–E–G#. Also symmetrical — one shape, three names.
add9 — add the 9th (the 2nd, an octave up) without adding a 7th: C–E–G–D.
9 / 11 / 13 — extended dominants. Each one implies everything below it, so C13 technically contains the 7th, 9th, and 11th too. On six strings you drop whatever matters least, usually the 5th and the 11th.
m7b5 — half-diminished. A minor 7th with the 5th flattened: C–Eb–Gb–Bb. The chord that starts countless minor-key turnarounds.
6 — add the 6th instead of a 7th: C–E–G–A. Warmer and more resolved than any 7th chord.
5 — a power chord. Root and 5th only, no 3rd, so it is neither major nor minor.

Reading them left to right

Suffixes stack in order, and each one applies to the result of the last. Take Cm7b5 apart:

Start with C major: C–E–G
m flattens the 3rd: C–Eb–G
7 adds the flat 7th: C–Eb–G–Bb
b5 flattens the 5th: C–Eb–Gb–Bb

The same method decodes anything. C7#9 is a C7 with the 9th raised a semitone. Cm(maj7) is a minor triad with a natural 7th, the bracket making it clear that maj7 describes the 7th and not the chord.

Different books, same chord

Notation was never fully standardised, so you will meet several spellings of the same idea:

maj7 also appears as M7, Δ7, or just Δ
m also appears as min or a dash, so m7 becomes -7
dim is often a small circle °, and half-diminished a circle with a slash ø
aug is often a plus sign, so Caug becomes C+

The Chord Dictionary's search box accepts the common variants directly, so you can type what the chart in front of you says rather than converting it first.

Making it stick

Reading the theory once will not do it. Pick a suffix you do not really know — m7b5 is a good candidate — open it in the Chord Dictionary, and look at the notes listed above the diagrams. Then play two or three voicings and listen for what the alteration actually did to the sound. Connecting the name to a noise is what makes the symbol readable at a glance later, when it goes past you in the middle of a song.