C 7♭9 Chord

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Formula R – ♭9 – 3 – 5 – ♭7

Summary

C 7♭9 is built from the notes C, D♭, E, G, B♭. The interval from C to D♭ is a minor 2nd (1 semitone), from C to E is a major 3rd (4 semitones), from C to G is a perfect 5th (7 semitones), from C to B♭ is a minor 7th (10 semitones). This chord contains 2 flatted notes.

The 7♭9 is a dark, aggressive altered dominant chord. It takes the tension of a dominant 7th and cranks it up with a lowered 9th, creating a sound that screams resolution — especially to minor chords.

Theory

Built from R, 3, 5, ♭7, ♭9, this chord is the go-to dominant chord when resolving to a minor chord. The ♭9 adds a half-step dissonance above the root that creates intense pull toward resolution. The interval between the 3rd and ♭9 outlines a diminished chord, which is why it shares the dim7's dramatic quality.

On the guitar

The most common shape places the root on the 5th string, with the ♭9 voiced on one of the upper strings. The 5th can be omitted. This chord often appears in turnarounds and is essential vocabulary for jazz and flamenco guitarists.

Advanced

The 7♭9 contains a diminished 7th chord within it (the 3rd, 5th, ♭7, and ♭9 form a dim7), which is why it resolves so powerfully. Try using it as the dominant chord any time you're heading to a minor chord — it's the standard sound in minor-key resolutions.

Piano