Chord Symbol Guide

Symbol structure

A symbol has three parts:

Examples include C, Cm7, C13♭9, and Cmaj7 / E.

The root and bass are spelled in the current tonal context. The middle portion is formatted from the identified chord quality and extensions, so notation and spelling preferences change its presentation without changing the underlying analysis.

Two compact notation styles are available. Before extensions and alterations are added, chord symbols start from these base quality labels:

Quality	Textual	Symbolic	Example
Major triad	no suffix	no suffix	C
Minor triad	m	−	Cm or C−
Diminished triad	dim	°	Cdim or C°
Augmented triad	aug	+	Caug or C+
Suspended triads	sus2, sus4	sus2, sus4	Csus4
Dominant seventh	7	7	C7
Major seventh	maj7	Δ7	Cmaj7 or CΔ7
Minor seventh	m7	−7	Cm7 or C−7
Half-diminished seventh	m7(♭5)	ø7	Cm7(♭5) or Cø7
Fully diminished seventh	dim7	°7	Cdim7 or C°7

The examples below use textual notation.

Headline extensions

The highest eligible natural extension becomes the symbol's headline on seventh-family chords:

• C7 with a ninth becomes C9.
• Cm7 with a supported eleventh becomes Cm11.
• Cmaj7 with a supported thirteenth becomes Cmaj13.
• C7sus4 with a supported ninth becomes C9sus4.

A headline communicates a stacked extension. It absorbs lower natural extensions that the headline conventionally implies:

• An 11 implies a ninth.
• A 13 implies a ninth, but does not require or imply a sounding natural eleventh.

Alterations remain explicit, so a dominant thirteenth with a flat ninth and sharp eleventh is C13(♭9,♯11).

Fully diminished seventh chords are an exception. Natural upper tones are shown as added tones, such as Cdim7(add9), rather than promoted headlines.

Extensions vs. added tones

A stacked extension is distinguished from a tone added outside that stack:

• A natural ninth is 9 when supported by a seventh; otherwise it is add9.
• A natural eleventh is 11 when supported by a seventh and some form of ninth; otherwise it is add11.
• A natural thirteenth is 13 when supported by a seventh and some form of ninth; otherwise it is add13.

A thirteenth requires a ninth but not a sounding eleventh, matching common practice where the eleventh is usually omitted from a thirteenth chord.

The supporting ninth may be natural or altered. For example, a dominant chord with a sharp ninth, sharp eleventh, and natural thirteenth can headline as C13(♯9,♯11).

Sixth chords use the conventional 6/9 spelling when an added ninth is present.

Why not add2 or add4?

Chord symbols describe harmonic function more than register. A D added to a C triad serves as the ninth whether it is voiced next to the root or an octave above it; the same principle makes F an added eleventh. The labels add9 and add11 are therefore used consistently instead of changing to add2 or add4 based on voicing.

sus2 and sus4 remain distinct because they describe replacement of the third, not merely an added tone.

Alterations

Altered upper extensions are written explicitly: ♭9, ♯9, ♯11, and ♭13. When a triad has an altered ninth without the harmonic support for a stacked extension, the symbol can use add♭9 or add♯9.

Altered fifths that define the base quality stay in its conventional quality label, including any parentheses, such as C7♭5, Cmaj7♯5, or Cm7(♭5).

Modifiers are ordered consistently by musical degree: ninths, elevenths, then thirteenths, with alterations placed alongside their degree.

Parentheses

Parentheses group modifiers when grouping improves readability:

• Multiple modifiers are grouped: C7(♭9,♯11).
• Added tones on seventh-family chords, including diminished sevenths, are grouped: C7(add13) and Cdim7(add9).
• Modifiers on suspended seventh-family chords are grouped to avoid ambiguous strings such as 7sus49.

A single ordinary modifier is normally inline: C7♭9, C13♯11, or Cadd♯9. Added tones on triad-like chords also remain inline because add already makes their role clear: Cadd9, Cmadd11, or Caugadd13.

Some house styles, including Berklee-derived teaching materials, parenthesize every tension and alteration, such as C7(♯11). Here, parentheses appear only when grouping or disambiguation aids reading, so a lone alteration stays inline as C7♯11.

Textual notation separates grouped modifiers with commas. Symbolic notation uses compact accidental symbols and no commas.

Omissions

Omission markers such as no5 and omit3 are not printed.

Omissions are properties of a particular voicing, while the displayed symbol names the best-supported harmonic identity. Commonly omitted tones, especially perfect fifths in extended chords, are understood as part of that identity rather than turned into a performance instruction. Dropping a structurally important tone is a different matter: it weakens the reading instead of simplifying the symbol.

This keeps symbols concise and avoids implying that a player should omit a tone merely because it was absent from the observed voicing. The literal notes remain available when that detail is needed.

Slash bass

A non-root bass is appended after a slash, as in Cmaj7 / E. The spaces around the slash distinguish bass notation from the compact 6/9 quality.

The formatter removes an added-tone label when the slash bass already supplies that same tone. For example, it prefers A♭7 / D♭ over the redundant A♭7(add11) / D♭. Similarly, a seventh chord whose only ninth is supplied by the slash bass is shown as C7 / D, not C9 / D.

References

These formatting decisions draw on both historical and modern practice:

• Carl Brandt and Clinton Roemer, Standardized Chord Symbol Notation (1976), an early effort to standardize symbols and remove ambiguity for sight-reading studio musicians.
• Chuck Sher and others, The New Real Book (Sher Music Co., 1988), representative of the modern jazz lead-sheet consensus.
• Mark Levine, The Jazz Theory Book (Sher Music Co., 1995), a modern pedagogical reference for the reasoning behind chord naming, extensions, and alterations.

Where these references differ, WhatChord favors the modern consensus and its own readability priorities while keeping their shared clarity principles.