On this stack post answer: Chord naming conventions: add2 versus add9

And on this website: https://www.brendanpauljacobs.com/spelling.htm

The writers imply that sus2 chords actually do not exist. There is another example on this page (around figure 5.33)


that says labelling a sus chord means it replaces the note immediately below it, therefore also making sus2 chords invalid (or at least rare as they no longer mean suspend the 3rd in this definition). The last example even goes on to imply sus9 is a real thing.

Which definition of sus is most accurate?

  1. sus2 and sus4 exist but nothing else.

  2. sus4 is the only valid sus

  3. sus replaces the tone below, so sus9 is valid too

  • 4
    4. whatever is actually used and how it is actually interpreted. Chord symbols, like any language, change and evolve. Somewhere along the line things like "5" have appeared, meaning a power chord. There was already "omit3" for that but it lost the popularity battle and now it's "5". "sus2" is actually used a lot however "invalid" it might be called. And "6" could be called "add6" to be more systematic, but it isn't called that. What are you trying to do with these valid/invalid things? Commented May 24, 2020 at 9:36
  • 3
    Define a rule set for software that will be familiar to most people, and that will also have an explanation for the final rules chosen. For example, thanks to Tim's answer I can give a reason why the software will deem sus2 to be a valid notation while also acknowledging its origins and the true notation for those who are curious.
    – Numpy
    Commented May 24, 2020 at 9:41
  • The explanation part seems interesting. To better model the way chord symbols are used, have the program show several options, with cultural styles and situations where each alternative might be used and why. One of my pet peeves is the half-diminished seventh chord, which often shouldn't be written at all in pop songs, because people play it wrong and ruin the harmony. If it's written like e.g. "Bm7-5" or "Bm7(-5)" in A minor, it often gets played as Bm or Bm7, playing an F# note instead of F. It should have been written as Dm6/B, Dm/B, or even just Dm, forgetting about the B in the bass. Commented May 24, 2020 at 10:02
  • @piiperiReinstateMonica - it only gets played wrong by those who don't know properly! Dm6 is beyond a lot - Dm6/B even beyonder!
    – Tim
    Commented May 24, 2020 at 10:08
  • You both can try typing in chord names to my web app now if you'd like. Currently it has no feature to go from notes to a chord name, and it does take in a wide variety of inefficient chord names which will eventually be corrected. This is so people can enter things they see on guitar sheets etc. and be educated on better notation. At the moment though there's no correction. Also, flats and sharps are to be written with b and # not - or +. www.chord.name
    – Numpy
    Commented May 24, 2020 at 10:17

6 Answers 6


Sus is short for suspended. The 3rd of a chord - major or minor - isn't there any more. It has been replaced (usually temporarily) by either the 2nd or the 4th from the scale using the same root note. Thus - C major = CEG. C minor = CE♭G. Csus2 =CDG and Csus4 = CFG.

There is actually the little-known fact that suspensions resolve downwards, which technically precludes 'sus 2' from being a suspension! It's really a retardation - which should resolve upwards. Thus sus 2 really should be ret 2, but I guess there's little need for that amount of accuracy! At which point, we'd only need sus and ret - the chord would be obvious from that!

Sus 9 is a new one on me. Never played it, or seen it written. Dominant 9, yes - C E G B♭ D. C maj 9, yes - C E G B D. Cm9, yes - C E♭ G B♭ D. C add9, yes - C E G D. But C sus9 seems to be pointless, and doesn't actually describe anything.

So, no.2 is strictly the only true fact. But - given its common usage, C sus2 has weedled its way into our lives to become accepted. I cannot see any other sus being useful or valid.

  • Comments are not for extended discussion; this conversation has been moved to chat.
    – Dom
    Commented May 26, 2020 at 17:10

The chord C-D-G exists and is very common, the only problem is what name to give it.
You can call it anything you like as long as the musicians who read your charts understand what you mean.

  • 'Csus2' is normally instantly recognized (even though it's technically not a suspension).
  • 'C2' is gaining in popularity (as is its counterpart 'C4').
  • 'Csus9' would be likely to confuse people.
  • Other contributors here have suggested 'Cret2', but that would really confuse people.

If there's a third in the chord as well, then you need a different notation: 'Cadd2' or 'Cadd9' depending on which you prefer.

  • C-D-G is also Gsus4! The name of the chord depends on the voicing (G-C-D) Commented Oct 12, 2021 at 11:49

There is certainly a thing where the 3rd of a triad-based chord is replaced by the 2nd. In traditional harmony it would be expected to resolve, and distinction was made between a suspension and a retardation. Today it might well not do so.

Some people are insistent it should be named as 'sus9'. They cite a 'rule' that chord names have no business trying to describe voicing, and that the 'pile of 3rds' structure is sacrosanct (though they don't seem to mind 'sus4'). However usage finds 'sus2' useful as well as 'sus9'. (And don't confuse them with 'add2' and 'add9', where the 3rd is added to, not replaced.)

  • I've never seen or played 'add9', so am sceptical, but need to know what it's supposed to resolve to. Sus resolves downwards, in theory, so it would have to go to tonic. Trouble is, by then, the 3 is back in the game, so we'd never know...
    – Tim
    Commented May 25, 2020 at 10:44
  • I find it fascinating you've never seen add9 Tim. This makes me realise even more that I'm going to eventually have to just pick a set of rules that I'm comfortable with and stick with them. I'm curious though, in your writings / readings is what would be a Xadd9 chord (1, 3, 5, 9) simply written as Xmaj9 and the 7th discretionary to play?
    – Numpy
    Commented May 25, 2020 at 12:19
  • 1
    @Numpy - sorry, of course I've seen and used 'add 9.'. Idiot moment - meant to write 'sus 9.
    – Tim
    Commented May 25, 2020 at 18:44
  • @Tim the 9-8 suspension is fairly unexceptional in figured bass, however, usually as part of a double suspension.
    – phoog
    Commented Sep 15, 2021 at 7:22
  • 'add 9' doesn't have to resolve anywhere. NOTHING has to resolve anywhere in modern usage. Popular music has long used a tonic add6 as a final chord. Or the even more juicy tonic add6 add9. A plain tonic add9 chord is currently the cliche ending chord for a musical theatre ballad.
    – Laurence
    Commented Sep 15, 2021 at 13:01

Sus2 does indeed exist. It's actually quite new.


I think you misinterpreted the last example you linked - I don't think there's anything about 9 being a suspension.

sus9 is a very popular chord - it's a suspended chord with a dominant 7th and 9th. Gsus9 would be G C D F A. Since D does not contribute to the sound, it's usually played as G C F A, which is often notated as F/G.

It sounds really nice when you have a cadence and want to finish on a dominant, but "ligher". Andrew Lloyd Webber uses it in half of his songs... it's the repeated chord in "Mr Mistoffelees", for example.

From the practical perspective, the idea of the sus chord can be distilled to "a major or dominant chord constructed so that the natural 4th is not a dissonance". It does not matter whether the third is somewhere in the chord, or whether you add natural 2 or not.

Actually, calling it a suspension or retardation is silly, since in modern music the sound does not resolve... so actually it's neither.

Half of the problems with the question and its answers is that people are mixing historical, prescriptive harmony of the early 19th century and modern-ish chord notation. Both are interesting and worth knowing, but the usual approach of applying the first to explain the latter does not work.

Addendum (after reading other answers and comments)

In the classical theory, suspensions are DEFINED by the fact that they resolve. If a bar begins with a C/G chord and then continues with G and ends with C, then the first chord is not "C" (even though it looks like C), but rather "G with suspended 3 and 5" or "G with C instead of B and E instead of D".

Which is why if someone claims to use "the real, classic music theory" in the context of a single chord, they are just being pretentious.

In modern music on the other hand - sus chords seldom, if ever, resolve. "Resolving" sus to major gives a very distinct "medieval", "church-like" sound (and begs for sus4 -> sus2 -> major). So yes, the name "sus" might come from the original classic idea of "suspending", but nowadays it's just a historical foot note.

So, what's the point of sus chords? Currently, there's no single music theory that works across genres and "explains stuff". It's mostly hand-waving and acting smug. But if you just take the common part of the "modern" theory and practice (on comping instruments, like piano and guitar), you might picture it like this:

Generally when we play a major or a dominant chord, ALL the sounds from the relevant major scale sound will "work well", except for the fourth (eleventh). In practice, when a pianist sees a C major chord and needs to play the chord with the left hand, they use multiple voicings: C-E-G, C-E-B, E-G-A-D (assuming the bassist is playing C), E-A-D, B-D-E-G... they all "work" for modern ears under most circumstances. There's just one note that would not work in the left hand: F.

It's the same for C7: default piano voicings include C-E-Bb, Bb-D-E-A, E-A-Bb-D. There's just one note from the C mixolydian that doesn't quite work with the C7 chord: F, the fourth note of the scale.

This is why you will generally not find 11 chords in the wild. When 11 is mentioned, it is usualy altered (#11 is nice).

A "sus" chord is a chord with the third removed (usually) or placed so that it doesn't clash with the fourth/eleventh (for example - high above). It has the interesting property of working like a dominant ("suspends" the tonic), but it is cononant with every note of the scale.

If you take this perspective, sus2 is not interesting... you can use 2 freely anyway, with any C major chord, including sus4. sus4 means: "we removed the source of dissonance from this chord, feel free to play any note of the scale over it".

  • Can you provide a source for this? Particularly the part where a suspension doesn't actually imply a suspension. This is extremely misleading, as for 1. A simple search of suspended chords will always yield the result that the 3 is to be omitted, and 2. Because if the 3 is included, then there are other ways of notating the chord you believe should be called sus. A chord with the intervals (1, 2, 3, 4, b7) is simply a dominant 11th chord like C11.
    – Numpy
    Commented May 26, 2020 at 14:09
  • @Numpy: the public internet is not a great resource for music theory... it's mostly tutorialized and fordummielized. There's plenty of great paper books though. Lesson number one you get from reading a couple of them, especially in different languages - is that there is a lot of knowledge, facts and even wisdom - but absolutely no consensus. I will amend my answer a bit.
    – fdreger
    Commented May 26, 2020 at 14:19
  • @Numpy: that was much longer than I intended, and still did not touch many subjects... it's also hard to find a single source for general things. It's just something that comes from reading multiple books and papers... If you want a good intro on modern harmony, you can read pretty much anything by Mark Levine.
    – fdreger
    Commented May 26, 2020 at 15:07
  • @Numpy: as for the sus chord with the third - show me an example of C11 chord in context and we'll analyse it together :)
    – fdreger
    Commented May 26, 2020 at 15:08
  • @fdreger - sorry to say, but having read Levine, I'm pretty unimpressed. There are many discrepancies between text and music, which in an educational book just shouldn't be there. I coped, but if I was a theory beginner, I'd be no wiser having read his book/s. Try Bert Ligon instead. And - C11 is not a sus chord. It has 3 and it has 11. There's no suspension - the 3s there all the time, not waiting for resolution.
    – Tim
    Commented May 29, 2020 at 11:04

Many combinations of tones can be notated in a variety of ways, some of which may be easier or harder to perform, and some of which may be easier or harder to analyze. Ideally, music will be notated in a manner which is both easy to perform and also easy to analyze, but sometimes it's not possible to satisfy both goals at once.

Notations like "sus2" are often used in ways which may impede analysis because they don't fit rules of harmony, but are instead designed to be more easily sightread than other notations which may be more "accurate", but would also be more complicated. If someone at a keyboard is sight-reading a song sheet, and some combination of the notes C-D-G should occur at a certain time, the notation "Csus2" is more likely to result in that happening than many other notations would be. Song sheets in keys with many sharps and flats often have chords which are nonsensical from a theory perspective for this reason, but that doesn't make them "wrong". From a theory perspective, the iv chord of Cb major would be Fb minor (Fb Abb Cb) but someone who encountered Fbm while sight reading a chord sheet would be less likely to play the correct notes, without undue hesitation, than someone who encountered Em.

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