Chord Symbols, Explained

Pianote  /  Chord Theory  /  UPDATED Dec 5, 2023

Uppercase M’s, lowercase m’s, triangles, numbers…chord symbols can be confusing!

Here’s a no-nonsense guide designed to quickly explain and decode chord symbols you may run across. For a more comprehensive review of the theory behind chords, check out How to Play ALL Piano Chords and Chord Theory 101.

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Anatomy of a Chord Symbol

We can break down most chord symbols into components that each tell a piece of the chord’s story.

CHORD SYMBOLS. Components of "Cmaj7#5" labelled. "C" is Chord Name: the root note of the chord and what the chord is built on and named after. "maj" is Chord Quality: the sound of the chord - major, minor, diminished etc. "7" is Extension: scale degrees to include in the chord that are beyond the root, third and fifth. "#5" is Alterations: further ways in which the chord is altered. In this case the fifth is raised.

Chord Name

eg. C, D♭

This is the first letter you’ll see and what the chord is named after. This note is the root of the chord, so our chord formulas will be based on its scale.

Chord Quality

Eg. M, m, Δ, dim

The letters here will tell you the overall sound of the chord, such as major (“maj” or “Δ” or “M”) or minor (“m”).

Chord QualitySymbols You Might See
No symbol**


*Some people use Δ to indicate any major tonality; while others use Δ as a shorthand for a major 7th chord.

**Major chords typically omit this component. So, it’s rare that you’ll see “Cmaj.” Most notation will just have “C.” Dominant 7th (eg. C7), power chords (eg. C5), and major 6th chords (eg. C6) also omit this component.

***Half-diminished chords are seventh chords and can also be expressed as “m7♭5.”

Chord Extension

Eg. 7, 9, 11, 13

If the chord contains more notes than the root, third, and fifth (triad), a number here will indicate an extension. For example:

  • Cmaj7: C major triad extended to the seventh (1-3-5-7)
  • Cm11: C minor triad extended to the eleventh (1-♭3-5-♭7-9-11)

Chord extensions are common in jazz.


Eg. ♭5, #5

Additional symbols may be tacked onto the end of the chord to indicate altered chord tones. For example:

  • Cm7♭5: A minor 7th chord where the fifth is flatted. (This is also called a half-diminished chord and can be notated as just Cø7.)
  • Cmaj7#5: A major 7th chord where the fifth is raised.

Other Symbols

These chord symbols can be particularly puzzling for beginners, so here’s a quick explanation:

  • “Add” chords: An “add” chord is when an extra chord tone gets added to an existing chord. For example, Cadd9 indicates a C major triad plus an added 9th.
  • C6/9: This indicates a 6th chord with an added 9th.
  • Minor major: A chord like Cm(maj7) is a minor major chord. You can think of this as a minor triad with an added major 7th interval. For example, Cm(maj7) is C-E♭-G-B where C-E♭-G is the minor triad and C-B is a major 7th.
  • “Sus” chords: This indicates that the third of a triad be replaced with another chord tone. For example, Csus4 means replacing the third of the C major triad with the 4th.
  • Slashes: You can think of a slash chord like C/E as “C major triad over E.” Play the C chord with your right hand over an E in the bass with your left.

Chord Symbols: Quick Reference

Here’s a summary of what you might see on a chord chart or lead sheet and what each symbol means.

Chord Symbols You Might SeeType of ChordChord Formula
C, CΔ, CmajMajor triad1-3-5
C-, CmMinor triad1-♭3-5
C+, CaugAugmented triad1-3-♯5
Co, CdimDiminished triad1-♭3-♭5
6th chord1-3-5-6
C5Power chord1-5 or 1-5-1
7, Cmaj7, CM7Major 7th chord1-3-5-7
Cm7, C-7Minor 7th chord1-♭3-5-♭7
Cm(maj7), CmM7, Cm♯7, C−M7, C−Δ7, C−ΔMinor major 7th chord1-♭3-5-7
C7Dominant 7th chord1-3-5-♭7
Cm7♭5, Cø7Half-diminished 7th chord1-♭3-♭5-♭7
Co7, Cdim7Diminished 7th chord1-♭3-♭5-♭♭7
Major 7th chord with extension1-3-5-7-9
Dominant 7th chord with extension1-3-5-♭7-9
Add chord1-3-5 + 9
1-3-5-6 + 9
Suspended chord1-4-5
C/ESlash chordPlay the chord on the left with your right hand “over” the note on the right with your left hand.

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Piano Chords and Scales book cover with keyboard design on iPad.

How to Interpret Chord Symbols

An important thing to remember is that when you see a chord symbol on a lead sheet, you don’t have to play every single note in that chord symbol.

For example, if you see C13, you don’t have to play C-E-G-B♭-D-F-A. That’s a lot of notes and it’ll sound muddy! Instead, musicians usually use chord symbols as a guide. So for C13, you may play C-E-B♭ with your left hand and improvise with D, F, and A in your right hand.

In jazz lead sheets, the extension number sometimes points to a note in the melody.

We hope you found this post helpful! Happy chording 🎹

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Charmaine Li is a Vancouver writer who has played piano for over 20 years. She holds an Associate diploma (ARCT) from the Royal Conservatory of Music and loves writing about the ways in which music—and music learning—affects the human experience. Charmaine manages The Note. Learn more about Charmaine here.

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