In guitar or generally in any musical instruments, what is the difference between sharp notes & flat notes?

For example : Are A♯ & B♭ the same? And are C♯ & D♭ the same? Does that make any difference in terms of the sound produced by instruments?

Any help appreciated :)

  • We have several other questions related to this, definitely look at the one Sergio links and search out the others :)
    – user28
    Aug 30, 2013 at 16:38
  • A frequency difference is what lies between most notes
    – user10164
    Apr 24, 2015 at 20:26
  • 6
    Don't confuse him. Or at least answer the simple question before going into a level of detail which, to be honest, isn't applicable to most of our playing. Within the terms of the question, yes, A# is the same note as Bb. You put your finger in the same place, the same sound comes out. Butt their r thymes wenn it is better two spell sonething the wright whey. Point taken?
    – Laurence
    Feb 10, 2017 at 13:48
  • @LaurencePayne Thanks. I was looking for a basic answer like this that would apply to someone without much experience in guitar. Eventually the other answers may make sense but your answer is good for me at his point.
    – Rich
    Oct 24, 2018 at 18:30
  • Thanks. I tried to make it an answer, but The Management felt it only worthy of comment status!
    – Laurence
    Oct 24, 2018 at 18:35

10 Answers 10


Actually it depends on the instrument.
Some instruments can produce different notes for A# and Bb, others can not.

There are different ways to intonate. On one side you have a just or harmonic intonation which is built on harmonics scale (each tone has a a matemathical relation between the base tone), this makes each tonality have its own intonation; on the other side you have temperate intonation which makes a compromise between frequencies and different keys, dividing the interval octave in equally distance semi-tones, to make possible one instrument to play in different keys, always using the same notes.

Here is a good explanation about this. Alsto worth to read this.

In practical terms, to be able to fine tune a chord (just/harmonic intonation in the guitar or different instruments playing/singing together) you must raise or lower some tones. Often the third in the chord needs adjustment. For example the third in F# chord (A#) should be higher than a Bb. If your instrument can't play it (like a piano) you land on tempered intonation, if you can play it (or bend the tone guitar/harmonica/etc) then you can get a just/harmonic intonated chord.

Wheat Williams posted this very clear table on his answer to another question. Notice how the third in the chord is higher or lower depending on the intonation model you are using. (the A# in my example of the F# major chord).

enter image description here

About the mathematical relation between tones in the harmonic scale:
(source here)

enter image description here

  • The explanation doesn't make sense. F chord third is A, there's no A# in it. Are you saying that A# and Bb may be slightly different notes, depending on the tuning of a particular instrument ? Pianos will be generally tuned in a temperate manner,so they will sound good in any key.
    – Tim
    Aug 30, 2013 at 8:06
  • 1
    I meant F# (major), corrected the answer. And in this case I play A# on the violin, or singing, with a different intonation (higher) that I would play a temperate Bb. Pianos are limited instruments regarding intonation models (just intonation or temperate intonation). Piano sounds good on a temperate intonated ensemble, but not on a baroque ensemble using just intonation.
    – Sergio
    Aug 30, 2013 at 8:49
  • 5
    True, but even in other context the problem comes up. When I play with string quartet, or with vocal music, we often discuss if we play temperate or just. If a piano is with, then there is no discussion :)
    – Sergio
    Aug 30, 2013 at 11:22
  • 1
    I'll add that the difference isn't only in pitch. Even in equal intonation, in which the pitches of A# and Bb are the same, you would use one or the other in certain contexts. You don't have a Bb in the F# major scale, except as an accidental, because it already has a B natural. Even as an accidental, it has a different meaning than an A#: it's a diminished 4th, not a major third (though they happen sound the same in equal intonation). This might not make sense to many amateur musicians, but when you start seeing music in terms of phrases and not just individual notes, it becomes important. Apr 24, 2015 at 20:07
  • 1
    In 5-limit just intonation A# is lower ( 976.5 cents) than B flat (1017.6 [2-fifths, then a minor sixth up], or 996.1 [two fourths up] ).
    – Dave
    Apr 24, 2015 at 22:17

Enharmonic notes are different, e.g. G# and A-flat, even though it is not always the case that instruments make different sounds for these different notes. These different note names are used to indicate differences in terms of the melodic or harmonic content of the music.

For example, in A minor, G# is frequently encountered as the "leading tone" back to the tonic. Notating this sound with an A-flat would mis-represent what is going on in the music. Similarly, writing an E major chord as E,A-flat,B does not correctly the harmonic relationship between the root of the chord and the third (or the fifth if it were indicated with a C-flat). This would just be a notational convention if it weren't the case that many instruments can and do express the differences between enharmonic notes in terms of the sounds that they make.

A key instrument in this regards is the voice: it is the most commonly encountered instrument with continuous pitch adjustment, and composing and analyzing vocal music was a key facet in the historical development of western music theory which is the context in which this question arises.

Going back to the leading tone in A-minor, a vocalist singing a capella will tend to raise the pitch of that note, relative to the corresponding piano note, a component of "expressive intonation". Slightly sharpening the note makes it's resolution to the tonic (A) more satisfying. Similar considerations apply in terms of harmonic content: an E-major chord is E,G#,B -- the G# indicating the note a third above the E; in a choral group, the people singing the G# will (usually) select there pitch to be consonant with the E's (which is different from the equal-tempered G# on a piano). These considerations apply to other continuous pitch instruments, in particular unfretted string instruments in an orchestra.

Going further would require delving into the historical aspects of tuning, temperament and intonation as well as overall description of functional harmony and melody...

Even though the keyboards and guitars that are the primary instruments used in popular music do not make different sounds for these different notes, accurately describing what is going on in the music, whether melodically or harmonically, requires differentiating between enharmonic notes.


Adding onto Sergio's excellent answer: There are multiple ways in which enharmonic notes (notes of essentially the same pitch with different names, such as A# and Bb) come into play, as it were. One is with respect to different tunings. Sergio's answer cites a table that concerns two tunings, equal and just. There are in fact lots and lots of tunings, many of which involve different compromises between equal temperament and Platonic, "natural" tunings (based on integer ratios). And so you'll see various differences between enharmonic pitches, so that the F# that shows up in a D7 won't necessarily equate with the Gb that shows up in an Ab7 (even though C shows up in both chords). An instrument tuned to play the former chord may not be able to play the latter well, and vice versa.

That example highlights another way in which enharmonic notes make a difference: music theory. This has no intrinsic impact on how the note sounds; rather, they are differences in how the note is used or interpreted. A D7 chord consists of the notes D, F#, A, and C. If you were to "spell" it D, Gb, A, C, that would sound essentially the same, but it would be marked wrong on an exam, because that second pitch is not being used as a Gb, but as an F#. That D7 will typically resolve to a G chord—major or minor—and in either case, the pitch a half-step down from G is being used as the seventh or leading tone of that G scale.

This also explains some accidentals in actual music that typically mystify beginning students, such as double-sharps and double-flats. Why notate something Fx, when G sounds the same? Such a situation often arises when you have a secondary dominant: a dominant chord resolving to a chord other than the tonic. If you're writing something in B Major, say, and you have a D# Major (V/vi) resolving to g# minor (vi), that D# Major should be notated D#, Fx, A#—not D#, G, A#, even though those pitches happen to be the same, because the note that resolves to G# should be Fx, not G.

This also applies to variously altered chords. The sharp 9 and flat 13 of "the" altered dominant seventh chord (aka tritone substitution) are shifted from their natural position, so that for our good ol' D7 chord, the sharp 9 would be E#, not F, and the flat 13 would be Bb, not A#. And so on.


A simple question deserves a simple answer. Here's my attempt at the latter: When sharps and flats were first invented, no, A# and Bb were NOT the same pitch. A# was a higher pitch than Bb. But try to imagine a keyboard in which there are enough keys per octave to make all the available sharps and flats playable. You'd have to have fifteen fingers on each hand and each finger would have to be a foot long. (More or less.) So musicians got together and decided (most of them) to create a compromise, in which A# and Bb ARE the same pitch, and D# and Eb ARE the same pitch. That compromise is called Tempering the Scale, resulting in a Tempered Scale (not, as one commenter said, a temperate scale, which would be an entirely different thing.) Since that compromise was made most keyboard and fretted instruments produce pitches in which, yes, A# and Bb ARE the same note. The answer to your question has changed over time.


On my guitar I have a frequency counter. Using the same string and the same fret ( A#--B flat )of course I will get the same value ( frequency ) If frequency is tone , and if the question is " Are the notes of A# and B flat the same " The answer ,using the above statements, has to be A# and B flat ARE the same tones. However, I will confess as you probably already can see I do not have a clue about music theory . I guess its all in the QUESTION

  • Hi Bob. Unlike online discussion forums, we don't go in for discussion or speculation. Have a read of How to Answer for some guidance. Your post doesn't really answer the question - but you could always edit it to improve it. Also, you don't need any thanks or signature in posts.
    – Doktor Mayhem
    Jul 7, 2017 at 18:50

For example : Are A♯ & B♭ the same? And are C♯ & D♭ the same? Does that make any difference in terms of the sound produced by instruments?

It depends.

  1. On a modern keyboard there is only one black key between the A and B (or C and D). This means they not only sound the same, but actually are the same. On that keyboard.

2.There are keyboards that differentiate between A# and Bb, one example is here: [http://www.gothic-catalog.com/Gothenburg_Sweden_The_North_German_Baroque_Organ_s/675.htm]

  1. As an orchestral player (I play the bassoon) the choice of A# or Bb (may) help me to understand the function of the tone in the chord. And when I understand the function of my tone, I may want to modify its pitch to make the chord sound better. I know that to sound its best a major third in a chord should be low, a minor third high. Many orchestras, once they reach a certain level, will do this kind of adjustment to get closer to a just intonation. A nice experiment is to play tonic and dominant on a modern keyboard, say C and G, and then sing the major third. Once you have a nicely sound chord, press down the third, E. The keyboard E will be quite a bit higher than what you are singing. Try the same with a minor third, Eb, and the keyboard will be low.

  2. As a small tidbit, my bassoon actually has both and Gb and F# tone hole. As it is a modern instrument they are very close in pitch, but on older instruments they were quite different. Air and mouth and lips are used to modify the pitch.


A# is slightly higher in pitch than a Bb. It has to do woth the naturally resonant harmonic differences in major and minor keys.

Musicians playing non-fretted string instruments naturally correct pitch. Good guitarists and musicians playing on a fretted instrument will also do so by slightly pulling the string sharp when needed.

I'm surprised the correct answer was downgraded.

  • 1
    It may also depend on what key the A#/Bb features in.
    – Tim
    Oct 1, 2016 at 17:30
  • It really depends on the context whether in a given tuning system A# or Bb is higher or lower than the other. Even in equal temperament where the pitch of the two notes are equivalent, they each represent very different concepts.
    – Dom
    Oct 1, 2016 at 18:44

Yes, technically it is. This is easy to see when you play a violin or viola. This is because if you do an A#, and if you play a Bb, then they will sound the same. If that was confusing, I am sorry.


Question: In guitar or generally in any musical instruments, what is the difference between sharp notes & flat notes? For example : Are A♯ & B♭ the same? And are C♯ & D♭ the same? Does that make any difference in terms of the sound produced by instruments?

My answer:

Technically and Scientifically they are precisely one and the same notes.

One person replied saying: "Some instruments can produce different notes for A# and Bb, others can not."

This statement is unfortunately not true from both a Scientific and a Technical standpoint. Here are the reasons:

The scientific and technical facts are: Let us take, for argument's sake, the first A just above middle C as a point of reference. Scientifically it is referred to as A4 and this note has a frequency of 440.000 Hz (Hertz is the unit of measure for frequency) A#4 and B♭4 both share the same frequency of 466.164 Hz C5 (the first C above middle C) has a frequency of 523.251 Hz C♯5 & D♭5 both share the same frequency of 554.365 Hz

I have a complete list of all the frequencies from A0 all the way up to C8. Each chord will ultimately also have its own specific unique frequency. This list of frequencies is of the utmost importance when designing, building and tuning virtually any musical instrument precisely. (This also applies to the programming of sounds of virtual instruments)

Personally, from a design, building, tuning and writing perspective, (by writing I refer to musical notation as found on sheet music), it makes no sense whatsoever to give the exact same note two different names. Just a little interesting tidbit: the pan flute or syrinx is apparently the 5th oldest instrument with the probability of it been the first ever instrument to be able to produce semi-tones. This is done by tilting the angle of the tube away from the player's body thereby changing the angle at which the air flows in/over the tube thereby effectively lengthening the air's travel in/over tube as it were to produce a lower note. The only way to play a sharp (let's use A#4 for this example) is to play the next note's flat (B♭4 in this instance). It would, for reasons thus historical, make sense to do away with sharps and refer to them only as flats for all the semi-tone notes. It has been said that the first organ was constructed based around the idea of the tubes on a pan flute.

(A note for those who would want to get upset at this logical suggestion/solution, it will most certainly not be the first time in history that all the music scores have been re-written to comply with the latest methodology/standards......)

Hope this information helps.

  • 1
    I kind of understand where you might be coming from, but this answer doesn't seem to consider the effect of temperament. A# and Bb might have the same frequency in equal temperament, but they don't necessarily in another system. The context is also quite important. If the note is a third, it might have a different tuning to the same note as a fifth.
    – endorph
    Feb 2, 2017 at 6:17
  • 1
    This answer is very good, but only from the 12edo angle, which admittedly is the one in common use today. There is a large raft of information missing, which is relevant to the question, about the older Pythagorean tuning, which was used (and still is for authenticity's sake) in period music, making it what it was.
    – Tim
    Feb 2, 2017 at 7:56
  • 3
    Donald - if you read through Sergio's excellent answer you will see why your answer is only correct for a small subset of musical theory. In reality there are differences, both scientifically and technically in various temperaments - you can even measure the difference in Hz.
    – Doktor Mayhem
    Feb 2, 2017 at 10:49

I think Answer #1 is more complex than the question asked. The direct answer is that no, A# and Bb are not the exact same notes. Though they are close, A# is slightly higher in pitch than Bb. It is possible to play both of these notes at their correct frequencies on some instruments, such as a violin or a singing voice, because the player can control the pitch of each note very precisely. However, the player has less precise control of note pitch on other instruments, such as guitars and pianos, and it would not be practical to add enough strings or frets to include all possible sharps and flats. As a compromise, guitars and pianos are tuned "temperately", meaning that they use the same note for both A# and Bb, and the frequency of that note is somewhere between the exact frequencies for A# and Bb. Most listeners do not notice that tempered notes are not precisely on pitch.

  • 3
    This answer is misleading. In equal temperament, A# and Bb are different notes that are on precisely the same pitch (and so share a key on a piano, for example). It's not that they're "off" from their "correct frequencies", it's that equal temperament defines them to be identical pitches. Instead of thinking of just intonation as "right" and equal intonation as "wrong" or "nearly right", it's important to recognize that they're different systems of temperament that have specific purposes. Apr 24, 2015 at 19:59
  • 2
    And it's not generally true that A♯ is higher than B♭. You're probably referring to a leading tone A♯ that's “gravitating” towards its B resolution. But apart from such leading notes, just-intonation actually tends to make sharps lower, compared to 12-edo tuning (because a sharp-note is more likely to be the third of a major chord). Apr 24, 2015 at 22:58
  • @leftaroundabout leading tones are also lower in just intonation; they are also usually the major third of a chord.
    – phoog
    Jan 12, 2016 at 18:12
  • @phoog: that's matter of considerable dispute. Pablo Casals used to insist that leading tones be rendered almost a quarter-tone higher than just intonation, to make it clear that you have not a harmonious third in a consonant chord, but rather an energic forerunner note, leaving the unrequiting dominant for the tonic. Jan 12, 2016 at 19:12
  • @leftaroundabout then Pablo Casals was not employing just intonation.
    – phoog
    Jan 14, 2016 at 1:04

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