My question is a general curiosity because on StackExchange and other sites I haven't found a complete answer that I can get my head around. I've read through the existing 13th discussions and am still just not getting what I'm after.

I get basic major and minor 13ths but when I get to something like this:

[1 ♭3 5 ♭7 9 11 ♭13]

Which in C is [A C E G B D F]

Is this an:

  1. Amb13 (A-♭13) which seems to fit with Am11 adding a ♭13
  2. Am11add♭13 (A-11?13) no idea what a shorthand for add might be as + is usually augmentation as I understand it so Am11+♭13 wouldn't make sense
  3. Am11b13 (A-11b13) (reading as Am11 with a flat 13th on top and no "add" required)
  4. some kind of mutant hybrid like Am7dim13 A-7o13 (reading as A C E G + B D F)
  5. A minor-major 11♭13 (A-^11♭13)
  6. An ever stranger slash chord like Am/G7

I know these aren't in common practice but is there any standard guidance on naming of 13ths with varying mods to the upper tones? I'm coming at this assuming it's all the tones starting with the root through to the 13th and you aren't playing with inversions.

Are these alterations? Extensions?

When naming do you:

  1. stop at the 7th and treat it like a 4+3 note polychord even though I believe that is generally reserved for two triads?
  2. stop at the 9th and add alterations to the 11th and 13th?
  3. stop at the 11th and add alterations to the 13th?

Apologies for the mind dump. Just throwing out a list of every direction my mind has gone in with this topic.

Any reference or guidance would be appreciated.

3 Answers 3


It would be Am11♭13. Alterations are always placed at the end of a chord after the base chord symbol.

If you look at the notes, you have all the notes for an Am11 A - C - E - G - B -D. For it to be an Am13 you would need an F#, but since you have an F instead you denote it as a ♭13 after the first part of the chord symbol hence the Am11♭13.

  • 1
    In the "boston school" way of looking at this, I would call it an "Amin7b13", in which notation the intermediate tensions between 7 and the altered 13 would be the "natural" available tensions...so the 9 and 11 would be considered incorporated by convention...and you'd deign to mention them only if you explicity wanted them voiced, or if they were also altered (i.e. b9, #11)
    – dwoz
    Oct 22, 2015 at 15:22
  • 3
    @dwoz in my experience alterations never imply any extensions due to how the alteration changes the relationship between notes in a chord. I also can't find any source that states an Am7b13 contains an implied 9 and 11. I'd be interested to see if you can find one.
    – Dom
    Oct 22, 2015 at 16:50
  • this has been my experience through 30 years of reading charts as a bassist and writing arrangements. Your answer is correct, but as has been mentioned elsewhere, there are as many conventions as there are cities/regions/genres. The thing about the notation is that it's all about pragmatically conveying as much info as possible to the player. If, for example, I saw an Amin7b9...I'd infer that a b13 was probably the rule of the moment as well, unless otherwise notated. If a CONVENTION is established, then it's more compact to notate the exception.
    – dwoz
    Oct 22, 2015 at 17:05
  • But when playing with others that ask you to play a Amin7b9 that may not be the intention as the chord symbols are well defined. It may work it may not, but the bigger point is be explicit with what you want.
    – Dom
    Sep 21, 2016 at 3:44
  • Again, Dom, it's all about convention. I daresay that the LESS information you have to notate (in something like a chord symbol, which is itself already a kind of shorthand) the more efficient it is for the player. In exactly the same kind of way that we notate a key signature at the left of the bar, and then ONLY notate deviations from that within the note stream, we rely on a "convention." if this convention I mentioned...that everyone on the bandstand has a common experience that we play XYZ when we see ABC notated on the sheet...then it all works. Clearly, not a universal thing.
    – dwoz
    Sep 22, 2016 at 19:54

Though Dom's answer is a good one, I thought I could contribute by saying, be open to making adjustments to common chord naming systems if it makes life easier for you (although your personal system shouldn't be too ambiguous to other musicians).

You may have noticed by now that there are many different chord naming systems (albeit many of them having similar conventions, like using a 7 to represent a dominant chord). The lack of a sole chord naming system, however, is proof that music is an evolving artform, and this is a good thing.

For the sake of brevity sometimes musicians exclude chord alterations from the chord symbol entirely, with the understanding that said exclusions are still applicable. For instance, some jazz musicians represent the chord [1 3 5 b7 b9 #9 #11 13] by simply the symbol 7b9, even though the 9 and 11 are also sharped, and the notes look like they spell out a 13th chord rather than just a 7th chord. In your example of A-11(b13), however, it is probably best to be explicit and not worry about this type of shorthand.

The point is you're making the first step to understanding chord names by seeing what systems other musicians are using, and to that end I would suggest picking up a book on the subject and seeing what system the author uses too. The next step, in time, is finding a system that's right for you.

  • Joeb, thank you. I agree and often resort to my own devices when notating something. More than anything I always like to investigate to see if I'm overlooking a standard approach to something. When it comes to chord naming, even the books I own conflict at times on the subject. Theory and standards... always open to interpretation it seems.
    – ceearrtee
    Oct 25, 2015 at 16:29

There are plenty of variations on chord naming, but I find the most commonly used to be either:

  • greedy extension seeking
  • lazy extension seeking

Your chord 1 ♭3 5 ♭7 9 11 ♭13 has all degrees available, so it's not the best chord to use as an example. Let's use 1 ♭3 5 ♭7 11 ♭13 instead.


Take the highest natural added note as extension 11. Use alterations for the any added note that has accidentals b13. Natural added notes are implied unless omitted from the chord 9. Omissions may or may not be specified in the chord name. long: Amin11 b13 no9 short:



Take the highest natural added note as extension, without skipping any functions, or take the quality if no such higher extension available b7 (since the 9 is skipped, we have to resort to the quality). Add all other added notes with the add syntax 11, b13. long: Amin7 add11 add(b13) short:



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