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C♯ 9♯11

chord·/chords/9-sharp-11/c-sharp/

The C♯ 9♯11 chord contains the notes C♯, D♯, E♯, F♯♯, G♯, and B.

Notes: C♯, D♯, E♯, F♯♯, G♯, B · Piano keys: C♯ D♯ E♯ F♯♯ G♯ B

Reviewed for accuracy · Last updated July 2026 · Maintained by Justin Evans

D♭ 9♯11
This is the same chord as D♭ 9♯11 — the same keys on the keyboard, spelled with flats.
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C♯
C♯ – D♯ – E♯ – F♯♯ – G♯ – B

Practice C♯ 9♯11

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Introduction

The C♯ 9♯11 chord is a six-note chord made up of C♯, D♯, E♯, F♯♯, G♯, and B.

Notes

Notes:C♯ – D♯ – E♯ – F♯♯ – G♯ – B

Key Signature

A chord has no key signature of its own, but the C♯ 9♯11 is the tonic (I) chord of C# Major, whose key signature has 7 sharps (F♯, C♯, G♯, D♯, A♯, E♯, B♯).

F♯C♯G♯D♯A♯E♯B♯

Order of sharps

Sharps are added to a key signature in a fixed order. Each new sharp key adds the next sharp on the list.

F♯C♯G♯D♯A♯E♯B♯

Mnemonic: Father Charles Goes Down And Ends Battle

Chords in the Key of C♯ Major

These are the triads built on each degree of the C♯ major scale:

C1C2C3C4FC5C6C7C8C#G#
I — C♯ Major (major)
DegreeNumeralChordQuality
1IC♯ MajorMajor
2iiD♯ MinorMinor
3iiiF MinorMinor
4IVF♯ MajorMajor
5VG♯ MajorMajor
6viA♯ MinorMinor
7vii°C DiminishedDiminished

C♯ 9♯11 — Frequently Asked Questions

What is the C♯ 9♯11 chord on piano?
The C♯ 9♯11 chord contains the notes C♯ – D♯ – E♯ – F♯♯ – G♯ – B. On piano, play these notes together to sound the chord.

Related Tools

Chord FinderLook up any chord — see the notes, hear it, and play along.Chord DrillTimed drills to build speed and recognition across all chord types.Practice RoomPlug in a MIDI keyboard and get real-time feedback on every chord and scale.Circle of FifthsVisualize key relationships, relative minors, and key signatures.MIDI MonitorLive MIDI message stream with note names, velocity, and a scrolling staff.

References & Further Reading

The note names, intervals, fingering, and harmony on this chord page are grounded in the following sources. Public domain treatises and scores are linked to their full text; primary data reflects piano.org's own interval-derived dataset.

  1. 1

    Goetschius, Percy(1889)

    The Material Used in Musical Composition

    Public domain treatise
  2. 2

    Riemann, Hugo(1896)

    Harmony Simplified (English translation)

    Public domain treatise
  3. 3

    Beethoven, Ludwig van(1802)

    Piano Sonata No. 14 in C♯ minor, Op. 27 No. 2 ("Moonlight"), i

    Public domain score
  4. 4

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