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Theory Guides

Chord Symbols

Every chord symbol is a compact notation that encodes root, quality, extensions, alterations, and bass note in a single string. This guide teaches you to read and write them fluently.

Symbol Decoder

Type a chord symbol below to parse its components.

Anatomy of a Symbol

Eight patterns that cover 95% of what you'll see on a lead sheet.

Cmaj7
Major 7th

Δ or maj before 7 signals a major seventh — dreamy, sophisticated.

Dm7
Minor 7th

Lowercase m or "min" = minor quality. 7 adds the minor seventh.

G7
Dominant 7th

A bare 7 means dominant — major triad with a minor seventh.

Bø7
Half-Diminished

ø or m7b5 — diminished triad with a minor seventh (not diminished).

Bdim7
Fully Diminished

dim7 or °7 — all intervals shrunk by a half step. Symmetrical.

Caug
Augmented

+ or aug — major triad with a raised fifth. Unstable, tense.

Gsus4
Suspended 4th

sus replaces the third with the 4th. Unresolved, yearning.

F#7#9
Altered Dominant

Sharps and flats after the 7 signal chromatic alterations.

Quick Reference

20 essential chord symbols with full names and notes.

SymbolFull NameNotes
CC MajorC E G
CmC MinorC E♭ G
C7C Dominant 7thC E G B♭
Cmaj7C Major 7thC E G B
Cm7C Minor 7thC E♭ G B♭
CdimC DiminishedC E♭ G♭
Cdim7C Diminished 7thC E♭ G♭ B♭♭
Cø7C Half-Diminished 7thC E♭ G♭ B♭
CaugC AugmentedC E G♯
Csus4C Suspended 4thC F G
Csus2C Suspended 2ndC D G
C6C Major 6thC E G A
Cm6C Minor 6thC E♭ G A
C9C Dominant 9thC E G B♭ D
Cmaj9C Major 9thC E G B D
Cm9C Minor 9thC E♭ G B♭ D
C11C Dominant 11thC E G B♭ D F
C13C Dominant 13thC E G B♭ D F A
C7b9C Dominant 7th ♭9C E G B♭ D♭
C7#9C Dominant 7th ♯9C E G B♭ D♯

How to Read Any Chord Symbol

  1. Root: Always an uppercase letter (A–G), optionally followed by ♯ or ♭.
  2. Quality: The triad type: nothing = major, m/mi/min = minor, dim/° = diminished, aug/+ = augmented.
  3. 7th: A number immediately after quality: 7 = dominant, maj7/Δ7 = major, m7 = minor.
  4. Extensions: Numbers beyond 7: 9, 11, 13 add color tones above the 7th.
  5. Alterations: Sharps/flats on extensions: ♭9, ♯11, ♭13 — written after the base chord symbol.
  6. Bass: Slash notation /X — the note after "/" is played in the bass, not the root.