I understand that the chord formed by the intervals 1-3-5-b7-9 is a 9th chord and that the intervals 1-3-5-9 (omitting the 7) create an add9 chord, but how do you properly define the chord created by the following intervals?


Is this an add♯9 chord?

Also is there an add♭9? or an add♯11 or add♭11? (ex: 1-3-5-♭9, 1-3-5-♯11 or 1-3-5-♭11)

And while we're at it can you name a chord using add♯13 or add♭13? (ex: 1-3-5-♯13 or 1-3-5-♭13) Or is this just improper?

I know this may seem obvious, but I have never seen a chord written as "add♯9" so I have to at least ask... What is the correct way to name these chords?


Since a ♯9 is essentially the same thing as a ♭3, you could essentially say that the intervals used to create this chord could be 1-♭3-3-5. How would you name that? You can't call it M(♭3) can you?

5 Answers 5


It depends how you want to look at. Practically if you told someone to play a Cadd#9, they would understand to play the notes C, D#, E, and G. However from a theoretical standpoint, most likely the name would not properly show function as technically there are two thirds in the chord (D# is an enharmonic equivalent to Eb).

I have seen this chord come up though in a different post and I earlier I concluded that it would best show its fucntion as an altered minor major chord. In the example of Cadd#9 the resulting chord would be EmM7#5.

As Tim points out you probably would not see this chord without the seventh which would help smooth out the dissonance and I don't think I've ever seen an altered extension (9,11,13) without some type of 7th. Most of the combinations of notes you list have two notes a half step apart which creates the dissonance above. He also pointed out why the add b11 and add #13 would not exits. Another thing to note, there are no add13 chords as a 6 chord would be used to notate a basic triad with a 6th.

Back to the main question these are the chords I would think "theoretically exits" although I wouldn't think add would be the best way to represent them:

  • add#9
  • addb9
  • add#11
  • b6(addb13)
  • 'add9' is more commonly found in acoustic guitar stuff.
    – Tim
    Jan 4, 2015 at 13:15
  • What about calling it an add♭3 chord? since technically a ♯9 is the same as a ♭3 and it is being "added" to the major triad, or am I breaking some rules there? I feel like you can't use "add" with thirds... but I haven't seen any rule about it explicitly stated.
    – tjwrona
    Jan 5, 2015 at 0:01
  • @tjwrona1992 "add" applies only to extensions (9,11,13).
    – Dom
    Jan 5, 2015 at 0:05
  • Okay thanks, I know these may be dumb chords you'd never see, but I've just been trying stacking thirds and seeing if I can name the chord it creates. It's sort of like a learning exercise. :) I actually have one more if you don't mind. What would you call 1-♭3-♭5-♭♭7-♭9? I get that the 1-♭3-♭5-♭♭7 forms a diminished 7th chord "°" for short, but would you be able to label it as °(♭9) or would it be more appropriate (from a theoretical not a practical standpoint) to call it °add♭9?
    – tjwrona
    Jan 5, 2015 at 0:11
  • @tjwrona1992 why don't you ask that as a new question as other people may have different ways to look at those sets of notes and since it is kind of a new question.
    – Dom
    Jan 5, 2015 at 0:15

Both answers (by Tim and Dom) are good ones. To add to these answers, I believe these rules of thumb will help break it down:

"Add" plus only the chord's root means that 7ths, 9ths, 11ths, and 13ths are not implied (strictly speaking). Only your #9 pitch should be added to the triad. So for Cadd#9, you would play the C triad plus D#, and that's it.

With no "add", all the decorative notes will be implied up to the number after the root. If the number is altered (e.g., b13), the lower-numbered decorative notes will not be altered, unless noted. So for Cb13, you would play the C triad, and Bb, D, and F would be implied, along with Ab. If the chord needed those lower-numbered notes to be altered, this would be included in the chord symbol (e.g., Cb9b13: C E G Bb Db F Ab).

Sometimes you will see both a number after the root, plus an "add", such as Cmaj7(add x). In this case, you'll play the C triad, the B, and then add the "x" pitch, but decorative notes between 7 and x will not be implied.

Finally, with 6th chords, much of the above does not apply. To clarify what I mean, a C6 chord does not follow the same rules as a C13 chord. Although 6 and 13 are the same pitches, a C6 chord does not imply b7, 9, and 11. But, "add" can be used for 6th chords, so C6add9 would be the C triad, 6, and 9 (but no b7, etc.).


Just like yourself, I've never seen it written, possibly because it is so discordant it wouldn't be used much! Yes, the Hendrix chord (A7#9) is similar, but the m7 part makes it more listenable.

Chords are basically 1-3-5 with other appendages marked appropriately, so 1-3-5-#9 would be called Add#9. Incidentally, # can be written as + so it could be Add+9.

The other examples can be similarly written - 'add' anything means just that. There may also be other ways of voicing or writing the four notes which give a different name. Add b11 will end up sounding like the original major so that won't exist, theoretically or practically. Add #13 will effectively be a dominant 7.


Yes, add#9 definitely exists and is common in jazz. Let's go through some background info first.

Chord Nomenclature
The nomenclature of chord naming works like this: If the chord has a 7th of any type (or something from the 7th family like the 6 or b6) then we can have 9ths, 11ths and 13ths in a chord.

ex) Cadd2 is CEG and D. This chord does not have a 7th (or 6th, which is a replacement for the 7th) so we would call the D a 2nd, rather than a 9th.

ex) Cadd9 requires us to have some sort of 7th as well. It could be CEGBD or CEBD (we don't need the 5th) or even CEGBbD, etc.

So, a true Cadd#9 would involve a B of some sort.

Upper Structure(US) Chords
To form all sorts of #9 (or 11th and 13th) chords we can use a concept called Upper Structures. These are a class of amazing chords that are generically defined as a polychord (a dom 7th shell, which is R3b7, plus some combination of 9, 11 and 13). I'm speaking purely from a piano standpoint. We can think of US chords as two chords in two different hands. The left hand(LH) will have the dominant 7th, while the right hand(RH) will have the 9th, 11th and 13th (the "colour" notes).

Here's an example of an US chord with a #9. Let's say we're talking about Cadd#9. The LH will have the notes C E and Bb. The RH will have the rest. #9 is essentially D# (or Eb if we rename it enharmonically). Let's call it Eb as it will be easier to understand the next part. We have 2 avoid notes (notes we're not allowed to include) in any US chord. These are always a perfect 4th from the root (F in this case) and a major 7th from the root (B in this case) because the 4th clashes with the 3rd of our Cdom7 and the B clashes with the b7 of our Cdom7 chord.

To fill in the rest of the chord, choose any major or minor chord that includes Eb, but does not include our avoid notes (F and B). Here's a list:

  1. Eb major (Eb as the root...Eb G Bb)
  2. Eb minor (Eb as the root...Eb Gb Bb)
  3. C minor (Eb as the third...C Eb G)
  4. Ab major (Eb as the fifth...Ab C Eb)

Cb major (Cb Eb Gb) wouldn't work because Cb is the same as B and that's an avoid note. Neither would Ab minor because it contains a Cb (avoid note).

Now that we have these 4 chords, we can combine our LH chord with any of these and we will get a #9 chord. If we use the Eb major chord, since it's a minor 3rd from our root (C), we would call the chord C USbIII (pronounced as C upper structure flat 3). For the Ab major example, we would call the chord C USbVI since Ab is a minor 6th above the root. If we choose C minor we would get C USi. Notice the use of large roman numerals for major chord upper structures and the use of lower case roman numerals for minor chord upper structure chords. Here are some example of what we would call the intervals in these chords:

ex) LH: C E Bb with RH: Ab C Eb gives us a C#9b13 chord a.k.a. C USbVI ex) LH: C E Bb with RH: C Eb G gives us a C#9 chord a.k.a. C USi

In general, forming chords based on using upper structures allows us to not have to worry about figuring out b9, 9, 11, #11, etc intervals. We can simply view the chord as a polychord.

Using Upper Structure Chords
In jazz, you can use them to replace dominant 7th chords or you can use them as passing chords that are used to get to a certain chord.

Here's an example of a typical "turn around" in jazz using the pattern I - VI - II - V (one, six, two, five). In the key of C major, I is CEG, VI is ACE, II is DFA and V is GBD. In jazz, we would use the 7th versions of those chords: I is CEGA or CEGB, VI is ACEG, II is DFAC and G is GBDF. No jazz musician worth their salt would play GBDF for the V chord, it's just too tame, hence upper structures! For your case, let's say we wanted to have the #9 interval in the chord.

For the V chord, #9 would be A# (G is the root).Let's call it Bb for simplicity. Our avoid notes in this case are 4 (C) and 7 (F#). What major and minor chords have a Bb, but do not contain C or F# (or their enharmonic equivalents which are B# and Gb respectively)?

  1. Bb major
  2. Bb minor
  3. G minor
  4. Eb major

So, we could play the V chord as an Eb/G7 chord, which means we have the notes G B F Eb and Bb. That's a very nice and lush chord to use in place of the typical GBDF!

Check out the wikipedia entry on Upper Structure chords for more details: enter link description here



Is this an add♯9 chord?


Adding the sharp doesn't change the way add chords work. The sharp means you're adding an augmented ninth rather than a major ninth. Over a root of C it would be a D♯. Over a root of B it would be Cx a double sharp.

The only things I can think would be a problem are:

  • Lots of people will misspell it. With a root of C it would be C E G D♯. It would not be C E G E♭. Your edit gives an example of a ♭3, a minor third. That would give you the spelling with E♭. Enharmonically they are the same, if you ignore the octave, but the spelling is different, you should choose the spelling based on what you really intend the harmony to mean.
  • Someone might not read the add and consider it a ♯9 chord - as in a dominant seventh chord with a sharp ninth. You could avoid that by using add♯2.

Jazz chord symbols don't specify voicing so there is no practical difference between add2 and add9. So, using add#2 could help avoid confusion with a ♯9 chord. The ♯9 chord is popular so if you really want to avoid that probably it's better to use add♯2.

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