C#6/9

Q: What notes are in the C#6/9 chord?

The C#6/9 chord (C# 6/9) contains: C#, E#, G#, A#, D#. Its interval structure is shown above in the Theory section.

Q: How do I build C#6/9 on the keyboard?

Take the root and add the remaining chord tones following the interval formula. The highlight shows chord content, while the inversion control changes which chord tone is in the bass.

Q: Which keys is C#6/9 found in?

The chord acts as a diatonic degree in several keys — they are marked on the circle of fifths in the "Harmonic context" block.

Q: What can I substitute for C#6/9?

A substitution depends on harmonic function and voice leading, not only on shared tones. Computed options appear in the "Substitutions" block and should be checked in context.

C# 6/9

Octaves

Musical context

ChordC# majorTriad

ChordC#6/9C# 6/9

ArpeggioC# majorBroken triad

ScaleC# major7 notes

KeyC# majorMajor key

ProgressionPop axisSequence

How the chord relates to the scale, mode, key and progression.

Theory

General info

Full name: C# 6/9
Symbol: C#6/9
Root: C#
Quality: 6/9

Chord notes

1C#root

3E#major 3rd

5G#perfect 5th

6A#major 6th

2D#major 2nd

Functions & resolutions

Typical function in key: ITonic (I)C# major
Stability / tension: Stable — can serve as major tonic
Most common resolutions: F#F# Major G#G# Major A#mA# Minor
Main resolution: C#6/9source
G#G# Major
Major chord C# is a stable tonic. As tonic it doesn't require resolution, but in a progression context typically moves to IV or V.
Other resolutions: C#6/9source
Deceptive resolution
A#mA# Minor
As the V degree, a major chord can defy expectations by moving to vi instead of I (deceptive cadence).
C#6/9source
Modal resolution
BB Major
In modal context, a major chord can freely move to bVII, bIII, or bVI — characteristic of Mixolydian mode.
C#6/9source
Jazz reharmonization
C#maj7C# Major 7
In jazz, a major chord is enriched to maj7, 6/9, or add9 and can smoothly transition into a ii-V of another key (modulation).
C#6/9source
Functional resolution
G#G# Major
As the IV degree (subdominant), a major chord can resolve to V or directly to I (plagal cadence).

Features

Character: Major, with 6th and 9th
Characteristic interval: 6th, 9th
Description: The major 6th and 9th extend a major triad without a 7th, so the chord retains tonic stability.
Application: Final chord in jazz and bossa nova
Soul and R&B
Alternative to plain major

Voicing & structure

Root position

v1C#(C#4)Bass

root

v2E#(E#4)M3from C#

v3G#(G#4)m3from E#

v4A#(A#4)M2from G#

v5D#(D#5)P4from A#

Harmony

Compatible scales

All chord tones are contained in these scales — use them for improvisation.

ScaleC# Major pentatonic ScaleG# Yo (Japanese)ScaleA# Minor pentatonic ScaleA# Blues scale ScaleC# Ionian (major)ScaleC# Lydian ScaleC# Mixolydian ScaleD# Dorian ScaleD# Mixolydian ScaleD# Aeolian (natural minor)

This chord on guitar 🎸

See how C#6/9 looks on guitar.

Explore

Circle of fifths

Highlighted major keys contain this chord among their diatonic harmonies.

Relative key: BbmBb minor
Dominant: AbAb major
Subdominant: F#F# major
Key signature: 5 flats (Bb, Eb, Ab, Db, Gb)

What to learn next

ScaleC# Ionian (major)Scale to improvise over this chord PracticeChord trainerLock the fingering into muscle memory ProgressionChord progressionsHow this chord works inside real progressions

Recommended for you

C# Ionian (major)A scale related to this chord

C# LydianA scale related to this chord

C# MixolydianA scale related to this chord

C# Chromatic scaleA scale related to this chord

Practice

Keyboard Trainer

Reinforce it in practice — play and name notes on the interactive keyboard.

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Test yourself

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What notes are in the C#6/9 chord?

How do I build C#6/9 on the keyboard?

Which keys is C#6/9 found in?

What can I substitute for C#6/9?