I have been working on the excellent book 'Melody' by Rikky Rooksby. There is some work on suspended chords and one example on a score showed the chord Fsus♯4. Now, working on the definition that on a suspended 4th the 4th replaces the 3rd by the note that is one high higher in the scale got me puzzled. Is this correct, is there such a thing and, if so, how? I thought it would be just Fsus4. After all the 4th note on the scale will just that, no matter what scale.

  • @Tetsujin a 4th above F will be some kind of B. Dec 6, 2019 at 17:00
  • Some info - key, or even a screenshot - would help a lot.
    – Tim
    Dec 6, 2019 at 17:24
  • @Tetsujin - Fsus4 is F Bb C. There's already an A as the 3rd, so 4th is Bb.
    – Tim
    Dec 6, 2019 at 17:35
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    to me, A sharp is the same thing as B flat. I really don't get all that theory stuff.
    – Tetsujin
    Dec 6, 2019 at 18:24
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    Thanks for the answers. I initially suspected it may be a misprint, but then it occurred later on. But I still think it is a misprint because it was a simple C major scale.
    – jonel
    Dec 6, 2019 at 21:54

5 Answers 5


Fsus♯4 should be F B♮ C.

Fsus4 would be F B♭ C.

In terms of the chord/scale system Fsus♯4 would be matched up with some kind of Lydian scale.

If F is the tonic and the B actually resolved, I would expect the B♭ to go down to an A and the B♮ to go up to the C. That upward resolution can be called a retardation instead of a suspension. Anyway, in pop and jazz chords with sus labels are often not treated as real suspensions, so these details may not matter.


Adding ♯ to a chord interval indicates augmentation.

Thus, sus♯4 means suspension with an augmented 4th (or tritone) instead of a perfect 4th. The chord in this situation is then F B C because B is an augmented 4th above F.


It's a perfectly good and useful chord, and in C major it is as Albrecht Hügli describes. I think most session musicians would quickly work out what was wanted. Bartok used it a great deal. [Though without the chord symbol obviously.]


It might be a misprint for F#sus4. It might be a loose description of F(add♯4) or even F(♭5).

If you show us the page in question, it might be clear which is intended.

As you've seen from answers and comments so far, it's unclear as a chord symbol and therefore its use is not to be recommended.


Not a chord I've ever come across. If indeed it is Fsus♯4, then its spelling will have to be F B C. As that stands, the B and C will technically be next to each other - otherwise that B would be named as ♯11. It's not, and the 3rd (A) would be retained. Although it wouldn't be the first time a chord has been incorrectly named..! Which I doubt sounds too good, anywhere.

Googling gives some examples of 'Fsus♯4, which turn out to be, unsurprisingly, F♯sus4, which gets spelled F♯ B C♯. Altogether more listenable! Dependant on the key and location in the piece, I'm going for the latter!

EDIT: another thought occurred - in key C, with a G note as bass, it sounds like a sus, playing FBC close in treble. That resolves nicely to C, by dropping the B to A, then change to C major, as a lot of sus chords actually do. But I wouldn't call it Fsus♯4. More like G11.

  • Good point, maybe the # is meant to be on the F rather than the 4 Dec 6, 2019 at 18:30
  • F#sus4 and Fsus#4 are totally different “flavors”. The first one is a standard suspended 4th with a note a perfect 4th above the root. The other has a augmented fourth above the root. Your last paragraph makes no sense to me.
    – b3ko
    Dec 6, 2019 at 22:20
  • @b3ko - I'm well aware that they are different 'flavours' - except I don't believe Fsus#4 exists per se. Please Google, and you, like me, will be presented with mostly F#sus4, although there are several postings of Fsus#4 which turn out to be wrongly named. Hence my answer. In 60 yrs of playing all sorts, I've never come across anything sus#4 - have you? Where?
    – Tim
    Dec 7, 2019 at 8:38

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