All I know is that:

  • if the song has an F chord then it should be flats
  • but if it has a B chord it should be sharps

In this song, the chords are Dm B♭ F C and a transition chord which is C♯dim/D♭dim

My question is do I use C♯dim or D♭dim?

For more context if needed:

Also, side question: is the key F or Dm?

This is important for the forum that I am uploading transcriptions to.

Edit: this question isn't specifically for this song.. It's in general. The song was just an example.

  • I think it’s not really possible to give a simple answer to the broader question of how to know whether to transcribe with a sharp or flat in every situation. There are too many variables and the decision is a complicated one. The more music theory you learn, the better you’ll understand when to use a sharp versus a flat. Commented Jan 29, 2021 at 15:58
  • 1
    What's the copyright status of this piece of music? I think SE shouldn't condone people being able to download a transcription of the piece, free, if they should buy a copy.
    – Rosie F
    Commented Jan 29, 2021 at 15:58
  • 1
    This is just a transcription request. You need to learn about keys and key signatures to do this. It isn't a Q&A topic. Commented Jan 29, 2021 at 17:02
  • 1
    You could strip out the entire "for more context if needed" section and still have a perfectly coherent and answerable question. This is very obviously not a transcription request.
    – Esther
    Commented Jan 30, 2021 at 21:35

4 Answers 4


The key signature says either F major or D minor. Sort of vague. Were there some C♯s in the piece, it would point more towards D minor - and I suspect the C♯ diminished chord could be used in evidence.

As far as changing key - obviously one is bound by the new key signature. If it went into E major, there'd be sharps, E♭ major, flats, but as far as diminished chords are concerned, we tend to take the lowest note as the root. They are symmetrical, so could have four (or more) names. I've seen the same diminished chord with different names in different places in the same piece.

Since in the original, that diminished leads to Dm, C♯o seems like a better option. So, transcribing it into, say, G major, it would become D♯o, into C major, it's G♯o - taking its name from the fact it's leading to the relative minor. But - if there was, say, in the last example, a bass note of D, it could be Do.

EDIT: the title needs addressing. It must mean accidentals, because the sharps or flats in the new key are a given. That can't be any other than one key signature. So, with that in mind, generally, in flat keys, additional accidentals are kept to flats, and vice versa. The reader already has his 'flat hat' on, so continuing with that mindset is good. There are occasions where technically an accidental neeeds to be disobeying that 'rule'. For example, in key F, if there's a C+, using C E and G♯, that accidental won't be correct written as A♭, even though the key sig. has a flat already. It also helps to explain the function of certain harmonies better that way.


First, to answer your title question, once you determine what the key of the song is then that will determine whether you use sharps or flats for the key signature. G,D,A,E,B are sharp keys and F, Bb, Eb, Ab, Db are flat keys. C is none and F#/Gb can go either way, 6 sharps or 6 flats.

Your first sentence isn’t really accurate. If instead of saying “has an x chord” you were to say if the song were in the key of F or B then you would be right about the flats and sharps in the key signature.

Now, getting to this tune, the diminished chord should be a C#dim because it functions as a vii diminished chord going to Dm despite the one flat in the key signature of either Dm or F.

EDIT: since you mentioned that this song is an example, I will add that in general you want to go with the accidental that is best explained by standard harmonic analysis. For example, in F if you have an Eb chord this is typically analyzed as a bVII chord so it would be Eb and not D#. You use the letter sequence that goes with the analysis, (7-1 = E-F)

As for the key, some might hear it in either Dm or F and can state a case for either but I think F makes the most sense. It seems to resolve there both harmonically and melodically. That makes it: vi IV I V, a pretty standard progression. Either way the key would be one flat.

  • I'm sure I've heard that sequence - only about a million times so far. To me it'd sound more in Dm with a v or V chord, which is absent. Although I suppose the C could count as a sort of dominant to Dm, but, it's actually the dominant of F, and there's I IV V and vi of that key present.
    – Tim
    Commented Jan 29, 2021 at 17:27
  • @Tim Good points. It CAN be interpreted as Dm but what makes it sound more like F to me is also the fact that the chorus melody is centered around F. It seems like a very large amount of pop tunes nowadays are written with nothing but the 1,4,5,6 chords in varying orders. Those progressions remind me of Neil Young’s “Heart of Gold” from back in the day. Commented Jan 29, 2021 at 18:38
  • Yeah, 1 6 4 5 was de rigueur back in the day. Still works well as an intro!
    – Tim
    Commented Jan 29, 2021 at 18:45

As a general rule, diminished chords are built on the seventh note of the corresponding scale and lead to the main chord of that scale. A typical use of C#dim would be leading to a D chord; a typical use of Dbdim would be leading to a Ebb chord.

Thus, with no other information, C#dim would be the better guess.

With the additional information that the song contains Dm, Bb, F, and C, that would further suggest C#dim -- as a lead-in to Dm. However, there is a complication: C#dim, Edim, Gdim, and A#/Bbdim all contain 3 of the same 4 pitches. So could it really be an Edim chord, which would make sense in the key of F?

Finally, listening to the song, it's confirmed that the diminished chord leads to the Dmin chord.

C#dim is the correct spelling for this chord

The piece as a whole is in Dmin. The end of a piece is the best place to determine the key, and the ending is where one usually puts the most stable chord. This piece ends on the C#dim chord, leaving us hanging, but we can still conclude Dmin, as that is the clearly implied resolution.


When deciding on enharmonic spellings and accidentals, harmony is usually considered from the common seven-note-scale perspective:

  • There are seven different scale degrees, using the letter names C D E F G A B (but not necessarily starting from C)
  • Each of the seven scale degrees can be in either natural, sharp or flat "mode". But only one of those at any given time, not e.g. sharp and natural at the same time.
  • Chords are constructed as stacks of thirds (even if voiced in different octaves)

If we assume that the song is in F major, the scale degrees are:

  • 1:F
  • 2:G
  • 3:A
  • 4:Bb
  • 5:C
  • 6:D
  • 7:E

Now you have a dim chord between the 5th and 6th degrees, and your question can be transformed to:

  • is the 5th degree switched to "sharp mode", making C at least temporarily be C#, or
  • is the 6th degree switched to "flat mode", making D at least temporarily Db?

If the 6th degree is flattened, then you basically wouldn't use a D as a melody note but you would use C, while the dim chord is playing.

If the 5th degree is sharpened, then you basically wouldn't use a C as a melody note but you would use D, while the dim chord is playing.

Out of these two options, if you try them out, it should be very clear that C# is the correct choice. This also means that you can see the dim chord as an A7/C# chord without the A. A7 chord is a stack of thirds with the scale degrees 3, 5, 7 and 2, with 5 being switched to sharp mode.

The 7-note scale system doesn't cover all modern and jazz harmony, where you might have adjacent chromatic notes sounding at the same time or more than 7 notes per octave, but it works for the commonly used chords+melody pop way of thinking.

Not the answer you're looking for? Browse other questions tagged or ask your own question.