I've was taught that whenever you write a run of notes going up, you should use sharps instead of flats; And whenever you go downwards, you should generally write flats instead of sharps. My question is: Which accidentals I should use when changing keys while moving against the flow of reading?

For example: If I was in the key of C Major and I was writing a downward run of notes and temporarily went into they key of E Major (4 sharps). Should I express it in the form of flats (making it easier to read, but harder to see the key change), or should I write sharps (making it harder to read, but easier to see the key change)?

I originally went with writing flats because it seemed easier to sight read. But if I had chords in the left hand, I'd end up with a lot of sharps in the left hand and a lot of flats in the right.

  • I don't think you should mix flats and sharps if you're intending to denote the same thing. If you're modulating to E then the natural choice would be sharps or a temporary change of key signature.
    – user28
    Jan 10, 2013 at 16:29

4 Answers 4


To answer your question broadly, you should always use what is going to read easiest for the performer. Putting a scale of flats in E major would be very confusing and unwieldy as E major contains four sharps and musicians are much more accustomed to reading sharps in keys where sharps naturally occur; such as E, A, or B major for example. Expressing E major as Fb major would be both unnecessary and is technically impossible as it would constitute 8 flats for the key signature; including double flats which aren't used often, except for special circumstances.

That said, the use of accidentals with respect to a key change are greatly affected by what the intended harmonic function is. Unless you're reading atonal or serial music, notes with accidentals largely have some sort of harmonic function attached to them. That is why they are called "accidentals" - because they reflect a harmonic or notational intent of a composer that isn't possible with the current key signature.

In this respect, the general rule that you use for writing scales can also be applied to modulating to different keys: use sharps to get to a "sharp" key, use flats to get to a "flat" key. There are some theoretical exceptions to this of course, but then again, there always are.

If you do that, you should be fine.

  • Re: "...musicians are much more accustomed to reading sharps..." That's actually not accurate. This is only the case for pianists and string players, and really only true of the inexperienced or mediocre among them. Out of courtesy, I'll leave it to you to revise if you wish. Jan 15, 2013 at 4:46
  • 1
    If you reread my answer, you will see that the quote you provided was with respect to the key of E major. In general, musicians expect to read sharps in the key of E major. As a composer, I am quite well aware of the reading tendencies of instruments at various levels of proficiency. Out of courtesy, I would respectfully suggest reading a post twice before commenting. Jan 15, 2013 at 18:02

If it's a key that uses sharps on the cycle of fifths use sharps. Likewise for flats. Almost every score I've played through has been written this way. Even if it calls for things are a little trickier to read. Also with regards to mixing sharps and flats it's normally for something wierd like the Phrygian major stuff you get in Klezmer.


The rules you have learned are generally sound advice, but music is now to the point where we performers generally have to be able to deal with those kind of problems pretty fluidly, but fortunately performers typically are at this point. The sharp and flat rule is particularly applicable to chromatic scales, but even this basic form of the rule is broken all the time when you skip down to a chromatically raised leading tone that then leans up to its neighbor.

In your case, especially, if the passage going down is clearly in E major, the player can easily see that ahead of time and will have no problem with it. I would be hard pressed to think of a case where it would be better to write e major in flats. The alternative would be the key of F-flat major in which every note is flat including a Bbb.

If that's not satisfactory, please send or reply with a photo of the passage if you are still unsure and I'd be happy to advise.


The rule you are citing only holds for chromatic figures. If you have changed keys, then you use accidentals that match the new key.

If you are using a chromatic figure to move to the new key, then follow the rules for a chromatic figures until you finally arrive in the new key, where you then use accidentals that match the key. For example:

C major chord, c b b-flat a a-flat g f-sharp (B7 chord) E major chord

  • A nice thing about this example is the avoidance of a direct transition from Gb to G#.
    – supercat
    Aug 31, 2019 at 18:00

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