I have a book that labels C, F, Bb, and D as a Csus4 chord. I get the F is the 4th to C, but why the dominant 7th and the 9th? Are those vital to a Csus4 chord, do they add to it, or is the book just wrong?

If anyone has the book, I'm looking at page 22 in Mark Levine's The Jazz Piano Book.

  • I have the book in question and it is definitely a Jazz book (also a great book IMO), so all the theory doesn't necessarily apply elsewhere, such as Rock or Country. Specific theories have specific "rules", such that Jazz and Classical theory often contradict each other or work in completely different ways, so to play or compose with the theory of either in mind is to try to replicate that genre. Commented Feb 4, 2015 at 1:56
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    Without using slash notation, this chord would be called C9sus4 (no 5th).
    – Matt L.
    Commented Feb 4, 2015 at 11:11

5 Answers 5


No, the 7th and 9th are not vital to a sus4 chord. A "regular" sus4 would just have root, fourth, and fifth (so C, F, G, in this case). That said, jazz seems to never play simple "regular" chords without adding at least a 7th. But the chord you have listed could probably be more accurately described as a C9sus4 (without the 5th, if you want to get really technical). Alternatively, it could be described as the folowing slash-chord: B♭/C, which might make more sense.

However, this type of chord often occurs on the fifth note (dominant) of the scale (so you'd likely see this chord in the key of F). In that case, it is a particularly common type of chord to use in jazz (basically a IV chord over the 5th scale degree) so it has its own name: the jazz sus chord, or a "dominant 9sus4 chord". It's important to note, though, that "jazz sus chord" is different from a plain old "sus4" (which, as I said is just C, F, G).

I've described jazz-sus chords once before, as an example where slash-chords are useful.


It is a sus4 chord I would not call it a Csus4 though. It's obviously an extension with a suspended third. I would instead call it a C9sus4 because you have everything up to the 9th (it's ok to omit the 5th) and the 3rd is suspended.


A standard triad with a bass note a tone higher than the root is often called an 11th.(Off the bass note name). Bb, D and F make up a Bb major triad, and the C is a tone above Bb. So it can be known as C11. The intro to 'Midnight at the Oasis' uses 5 of these 11th chords. Otherwise known as Bb/C, but, as the others have said, it's not a sus4 in its common form.Could be Bb add 2,or at a push add 9 though unlikely, but generally the 'sus' bit suspends the 3rd of the chord, to be replaced, usually temporarily, with either a 2 or a 4. Not in this case.


These four notes don't make a sus4 chord, and certainly not a Csus4 chord. If you leave out the D, the other notes make an Fsus4. No other sus4 chords can be made from these four notes. However, like all sus4 chords, the three notes used for Fsus4 (F, Bb, C) can also be thought of as two other suspended chords: these are Bbsus2 and an incomplete C7sus4 (it has no 5th).


Need to recognize the difference between a triad sus4 and a dominant 7th sus 4:

Csus4 = C F G

C7sus4 = C F Bb D

So in the book it's a typo, should be "C7sus4"

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    I think C7sus4 would be C F G Bb...
    – mey
    Commented Feb 9, 2015 at 21:48
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    yes you can voice it that way. or you can drop the g and add the ninth Commented Feb 9, 2015 at 22:59
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    @MichaelMartinez - once there's a 9th in the chord, it ceases to be merely a 7th in name. It must be a 9th chord, and all ninths will have a 7th too. Except 'add 9'.So C7sus4 is CFGBb. C11 will have an E as well.
    – Tim
    Commented Feb 10, 2015 at 9:14
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    @mey - most times a 9th chord can be used to replace a 7th. Usually sounds richer or more sophisticated!
    – Tim
    Commented Feb 10, 2015 at 9:15
  • @Tim. you are correct. But a lot of times when a chord is written as a 7th it is implied that you can use the other tensions as you see fit. harmonically if you continue to keep the 3rd and 7th it still functions as the 7th chord. Or in this case the sus note (4th) and the 7th. Commented Feb 10, 2015 at 19:04

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