Guitar Chord Dictionary: C# Dominant Thirteen Flat Nine Chords

C# 13(b9) guitar chord shapes

C#13(b9) (C# thirteenth flat nine) follows the formula 1, 3, 5, b7, b9, 11, 13, so on C# it reads C#, E#, G#, B, D, F# and A#.

Its core is the dominant seventh C#7 (C#, E#, G#, B), with the flat ninth D, the eleventh F# and the thirteenth A# stacked on top. Try the C# Half-Whole scale over it: built from alternating half and whole steps, it holds every chord tone except the eleventh.

The eleventh F# sits a half step above the major third E#, a close neighbour. On a chart the chord may also appear as 13b9.

C# 13th with flat 9th guitar chord is also written as C#13(b9), C#13b9 or C#13-9.

Notes of the C# 13(b9) chord:

C# E# G# B D F# A#

Chord Structure:

Formula: 1 3 5 b7 b9 11 13

Play This Chord With Other Roots

C 13(b9) | D 13(b9) | E 13(b9) | F 13(b9) | G 13(b9) | A 13(b9) | B 13(b9) | C#13(b9) | D#13(b9) | F#13(b9) | G#13(b9) | A#13(b9) | Ab13(b9) | Bb13(b9) | Db13(b9) | Eb13(b9) | Gb13(b9)

Giancarlo Facoetti, founder of FaChords Guitar

Created by

Giancarlo Facoetti

Giancarlo is a musician (teaching guitar since 2000), software engineer, AI consultant and published researcher

FAQ

What are the notes of C#13(b9)?

C#13(b9) is spelled C#, E#, G#, B, D, F# and A#. It stacks a major third, perfect fifth, minor seventh, flat ninth, eleventh and thirteenth over C#.

What does the b9 mean in C#13(b9)?

It is the ninth lowered by a half step, which gives D, only one semitone over the root C#. That close, tense note is the signature of this chord.

Is C#13(b9) the same chord as Db13(b9)?

Yes, they sound identical. Db13(b9) is spelled Db, F, Ab, Cb, Ebb, Gb and Bb, so only the note names change.

Which scale goes with C#13(b9)?

The C# half-whole scale fits all the chord tones except the eleventh, F#. It includes the flat ninth D and the thirteenth A#.