How to decide if F#9 is f sharp dominant ninth chord or f dominant sharp ninth chord? Similarily for Gb9 also

4 Answers 4


Simple answer: Written as F#9 it is most likely an F sharp chord with a ninth. An F chord with a sharp nine would probably be a dominant chord and be written as F7#9.

Elaboration: Thanks for the comments! So just as F#13 is short for F#7,13, an F#9 can indeed be short for F#7,9. In my practice, I have rarely seen it abbreviated like that – maybe because of the ambiguity you're asking about. So in theory, F#9 can actually be both.

What do we do to disambiguate? Here are a few options:

  1. If you mean a dominant chord with a sharp ninth, use F7#9. If you mean an F# chord with an added ninth, use F#add9.

  2. You could also try to use space or parentheses to make things clear: F# 9 and F #9 or F#(9) and F(#9).

  3. In handwriting (or with superscript on a computer) you can make the meaning clearer by superscripting the options in smaller text.

I feel the least ambiguous solutions are F7#9/F#add9 and F(#9)/F#(9).

  • 3
    By the way, F#9 typically means "F# seventh chord with major ninth". See jazzbooks.com/jazz/FQBK p. 15 for reference. Aug 4, 2020 at 14:38
  • How would you write an F chord with a sharp nine, but without a seventh? But of course, nobody will actually encounter such a thing in real life, so F#9 means an F# 9. Aug 4, 2020 at 16:10
  • @piiperiReinstateMonica I would write Fadd#9 to denote F A C G#, analogously to how Fadd9 means F A C G. Aug 4, 2020 at 22:42
  • @user1079505 on what page of the Aebersold guide is the example? I don't see one with a plain #9. It's not totally complete or consistent, but the examples I see with altered ninths also include the 7 figure. Aug 5, 2020 at 14:51
  • @MichaelCurtis p. 15 (printed number). I was referring to "X9" chord symbol. Indeed, normally #9 appears only in altered chords (which are dominant seventh chord). A chord that would contain #9, 3 and no 7 would be either something departing from functional harmony, or a strong suggestion for specific voicing – I have never met something like that in literature. A chord symbol would be Fadd#2 or Fadd#9, I believe. Aug 5, 2020 at 15:23

Just seeing F♯9, I'd play F♯, A♯, C♯, E and G♯, producing a dominant 9th on F♯.

Context usually helps, though, and the following chord would be a big clue. If it was B♭, then the chord in question would most likely be F7♯9.


Chord names will never occur isolated! Context would help like Tim says. The writing with the computer keys is F# 9 = Fsharp 9 or F #9 = F7 #9, but normally the printing of a notation program or professional layout should be F# (sharp=subscript)and 9 or F (#9=superscript). Everything else (as asking without context) is just confusing or fishing for reputation points ;)


I have not seen it written, but the "rule" seems to be don't omit 7 when extensions are altered.

So, in this questions the 7 is omitted, therefore the 9 isn't altered.

Accidentals are suffixed to the right of letters but prefixed to the left of numerals. That sets up the ambiguity and something needs to added - or superscript used - to delineate whether the accidental is a suffix or prefix.

Some examples with the numerals given in parenthesis. As you drop supposedly unnecessary numbers and parenthesis you eventually get the ambiguous F#9 twice...

F(7)(9)   => F(9)   => F9

F(7)(#9)  => F(#9)  => F#9 

F#(7)(9)  => F#(9)  => F#9

F#(7)(#9) => F#(#9) => F##9

I suppose you could put back the parenthesis F(#9) but keeping the seventh F7#9 seems clearer to indicate an altered chord. Otherwise assume the extension is not altered and the accidental applies to the letter.

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