Chord Symbols and Chord Formulas

Chord symbols are a compact way of describing harmony. A symbol such as C, Am7, G9 or Fmaj7♯11 does not tell you one fixed guitar shape. It tells you which notes or intervals define the chord.

Once you understand that, chord symbols stop being a list of shapes to memorise and become instructions you can decode. This lesson provides the foundation for building your own voicings later.

C♯m7♭5

RootQualityExtensionAlteration

This lesson focuses on	Why it matters
Reading common chord symbols	Recognise each instruction contained in the notation.
Converting symbols into interval formulas	Build the harmony from any root instead of recalling one fixed shape.

Start with the Root Note

The first part of a chord symbol is the root. It acts as the reference point, and every other note is described by its interval from that root.

Chord nameC major

NotesC · E · G

Formula1 · 3 · 5

Chord	Root	Notes	Interval formula
C major	C	C – E – G	1 – 3 – 5
G major	G	G – B – D	1 – 3 – 5
D major	D	D – F♯ – A	1 – 3 – 5

The notes change, but the structure stays the same. A chord name tells you the root; the chord type tells you the interval structure.

Major, Minor, Diminished and Augmented Chords

The four basic triad qualities can be understood as alterations to the same three-note framework.

Major1 · 3 · 5

Minor1 · ♭3 · 5

Diminished1 · ♭3 · ♭5

Augmented1 · 3 · ♯5

Quality	Common symbols	Formula	C example	What changes?
Major	C	1 – 3 – 5	C – E – G	A root by itself normally means a major triad.
Minor	Cm, Cmin, C−	1 – ♭3 – 5	C – E♭ – G	The major third is lowered by one semitone.
Diminished	Cdim, C°	1 – ♭3 – ♭5	C – E♭ – G♭	Both the third and fifth are lowered.
Augmented	Caug, C+	1 – 3 – ♯5	C – E – G♯	The major third remains and the fifth is raised.

If you know a formula, you can build that chord quality from any root. You do not need to memorise every chord as a completely separate object.

Reading Seventh Chords

A seventh chord adds some form of seventh to the basic chord structure. The symbol becomes more specific because the quality of the triad and the quality of the seventh both matter.

Cmaj71357

C7135♭7

Cm71♭35♭7

Chord type	Common symbols	Formula	Notes from C	Reading rule
Major seventh	Cmaj7, CMaj7, C△7	1 – 3 – 5 – 7	C – E – G – B	“Major” describes the natural major seventh.
Dominant seventh	C7	1 – 3 – 5 – ♭7	C – E – G – B♭	A plain 7 means a flattened seventh.
Minor seventh	Cm7	1 – ♭3 – 5 – ♭7	C – E♭ – G – B♭	Both the third and seventh are flattened.
Minor-major seventh	Cm(maj7)	1 – ♭3 – 5 – 7	C – E♭ – G – B	A minor triad carries a major seventh.
Half diminished	Cm7♭5, Cø7	1 – ♭3 – ♭5 – ♭7	C – E♭ – G♭ – B♭	A diminished triad receives a minor seventh.
Diminished seventh	Cdim7, C°7	1 – ♭3 – ♭5 – ♭♭7	C – E♭ – G♭ – B♭♭	The double-flat seventh sounds like a major sixth but is spelled as a seventh.

Suspended, Added and Sixth Chords

The important question is whether a number replaces a chord tone or is added to the existing triad.

Replace the thirdCsus21 · 2 · 5

REPLACEADD

Keep the thirdCadd91 · 3 · 5 · 9

Symbol	Formula	Notes from C	How to read it
Csus2	1 – 2 – 5	C – D – G	The 2 replaces the third, so the chord is neither normally major nor minor.
Csus4	1 – 4 – 5	C – F – G	The 4 replaces the third.
Cadd9	1 – 3 – 5 – 9	C – E – G – D	The major triad remains intact and the 9 is added.
C6	1 – 3 – 5 – 6	C – E – G – A	The 6 is added to a major triad.
Cm6	1 – ♭3 – 5 – 6	C – E♭ – G – A	The 6 is added to a minor triad.

Extensions Beyond the Seventh

Extensions continue the same scale system beyond the octave. The larger number describes how the note functions inside the chord, even when it shares a pitch class with a simpler interval.

2+ octave9

4+ octave11

6+ octave13

Symbol	Full theoretical formula	Key distinction
Cadd9	1 – 3 – 5 – 9	No seventh is implied.
C9	1 – 3 – 5 – ♭7 – 9	The dominant seventh is implied by the 9.
C11	1 – 3 – 5 – ♭7 – 9 – 11	The full formula contains six notes, though practical voicings often omit tones.
C13	1 – 3 – 5 – ♭7 – 9 – 11 – 13	Seven theoretical pitches cannot all appear as different notes on a six-string guitar.
Cmaj9	1 – 3 – 5 – 7 – 9	Built on a major-seventh chord.
Cm9	1 – ♭3 – 5 – ♭7 – 9	Built on a minor-seventh chord.
Cmaj13	1 – 3 – 5 – 7 – 9 – 11 – 13	The “maj” specifies the underlying major seventh.
Cm11	1 – ♭3 – 5 – ♭7 – 9 – 11	The “m” specifies the underlying minor quality.

Reading Altered Chords

Altered symbols tell you to raise or lower a specific note. Read the base chord first, then apply the alteration.

1 · RootG

+

2 · Quality3 · ♭7

+

3 · Extension13

+

4 · Alteration♭9

Symbol	Base chord	Instruction	Resulting formula
C7♭9	C7 = 1 – 3 – 5 – ♭7	Lower the 9	1 – 3 – 5 – ♭7 – ♭9
C7♯9	C7 = 1 – 3 – 5 – ♭7	Raise the 9	1 – 3 – 5 – ♭7 – ♯9
C7♭5	C7 = 1 – 3 – 5 – ♭7	Lower the 5	1 – 3 – ♭5 – ♭7
C7♯5	C7 = 1 – 3 – 5 – ♭7	Raise the 5	1 – 3 – ♯5 – ♭7
G13♭9	G dominant extended harmony	Add the 13 and flatten the 9	1 – 3 – 5 – ♭7 – ♭9 – 11 – 13

Do not try to interpret a complicated symbol all at once. It is simply stacking instructions.

Slash Chords and Bass Notes

A slash chord specifies the bass note. The chord remains the harmony shown before the slash; the note after it must be the lowest note.

C/EChordBass note

Symbol	Chord	Required bass note	Meaning
C/E	C major	E	C major with E as its lowest note.
G/B	G major	B	G major with B in the bass.
Dm/C	D minor	C	D minor with C in the bass.

Slash chords often create smoother bass movement or specify an inversion. C/E does not mean “C chord followed by E chord”.

Chord Symbols Do Not Specify One Guitar Shape

Consider Cmaj7. The symbol defines the formula 1 – 3 – 5 – 7, giving the notes C – E – G – B. It does not dictate how those notes must be arranged on the instrument.

SymbolCmaj7C · E · G · B

OpenClosedSpreadInversion

The symbol defines	The player still chooses
The root and required harmonic quality	Which string contains the root.
The chord tones or interval formula	Which octave each note appears in.
Any extension or altered tone	Whether a note is doubled or omitted.
A bass note when slash notation is used	Where on the fretboard the chord is played.

Different arrangements of the chord tones are called voicings. Reading the symbol is the first step; constructing and choosing voicings is where the series goes next.

A Method for Decoding Any Chord Symbol

When you encounter an unfamiliar chord, work through the symbol in the same order every time.

Step	Question	F♯m9♭5 example
01 Find the root	Which note is the reference point?	F♯
02 Identify the basic quality	Is the triad major, minor, diminished or augmented?	m = minor: 1 – ♭3 – 5
03 Read the seventh or extension	Does a larger number imply a seventh?	9 gives 1 – ♭3 – 5 – ♭7 – 9
04 Apply alterations	Has a particular interval been raised or lowered?	♭5 lowers the fifth
05 Check the bass	Is there a note after a slash?	F♯m9/A would require A in the bass

Worked Examples

Symbol	Root	Quality and extension	Formula	Notes or bass instruction
Am7	A	Minor seventh	1 – ♭3 – 5 – ♭7	A – C – E – G
D9	D	Dominant seventh plus 9	1 – 3 – 5 – ♭7 – 9	D – F♯ – A – C – E
Gmaj7/B	G	Major seventh	1 – 3 – 5 – 7	G – B – D – F♯, with B lowest

Common Chord-Symbol Mistakes

Mistake	Incorrect assumption	Correct reading
C7 and Cmaj7	They are the same seventh chord.	C7 = 1 – 3 – 5 – ♭7; Cmaj7 = 1 – 3 – 5 – 7.
C9 and Cadd9	Both simply add a ninth.	C9 includes ♭7; Cadd9 does not include a seventh.
Sus and add chords	The 2 or 4 is always added.	A sus chord replaces the third; an add chord keeps it.
One shape per symbol	Every chord name has one correct guitar fingering.	The symbol describes harmonic content, not a fixed fretboard shape.
Playing every chord tone	Every theoretical note must be present.	Large extended chords often require clear, practical omissions.

The Key Idea

Chord symbols become much easier when you stop thinking of them as names for shapes. They are interval formulas built from a root.

Root+Quality+Extensions+Alterations+Bass

If you can identify those five components, you can decode almost any common chord symbol. The next question is no longer “Which shape have I memorised?” It becomes “Where can I find these intervals on the fretboard?”

That is the basis of chord voicing, and it is where the next lesson begins. In the meantime, use the Chord Finder to compare formulas with playable guitar voicings.

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