this is a basic question but I can't wrap my head around it : when you are using the interval formula for the minor scale (or any scale) how do you know if you should use flat or shaps as the semitones?

I know this is really simple, but I'm learning on a guitar and I don't sight read and I cannot work it out. I want to be able to work out scales without learning them all by heart. Thanks


5 Answers 5


You get that in two ways:

  • the key signature
  • conventions about altering tones of a key.

Let's use an example of E minor, that's really common for guitar. The key signature is one sharp, an F#.

Add to that the general handling of accidentals and tones of the key where you can think of things this way: each key should always have the seven letters A-G with no skipped or repeated letters.

So, you have E F# G A B C D E. Notice all letters are used, none are repeated (excluding the scale repeating at the octave.) The F gets a sharp to raise it. The G is not lowered with a flat, because that would involve skipping F altogether and also you would repeat the G with G natural and G flat.

When you add accidentals in the minor scales - like using D# in E minor - apply this same principle about letters.

You don't lower the E to Eb - that would involve duplicate letters - change the D from natural to D#.

Finally some things are just conventions of key signatures where typically you use a key signature with the fewest sharps or flats. So, C# minor is used instead of Db minor, because the 4 sharps of C# minor is simpler than the 6 flats and double flat of a Db minor (theoretical) key signature.


Quite simple! Each scale - major and three minors - have one of each letter name. So to decide whether in a particular scale, it's a C♯ or a D♭, which are both the same note soundwise - enharmonic - you need to count up from the start note, called the tonic. If there's a C of some sort there already, it must be called D♭, but if the one before is a B something (B♭, B♮) then that note will be called C♯.

Bear in mind there are three different minor scales, but every one will still have each and every letter name in it.

Let's do a little demonstration: the A minor scale. From what's stated earlier, the notes will be (some sort of) A B C D E F G. Making this the natural minor, with a key sig. of no ♯ or ♭, the notes will be , surprise, surprise - A B C D E F G. For the harmonic minor scale, there's going to be a raised leading note (the 7th), so now, the scale is A B C D E F G♯. For the rising melodic or jazz minor, there's also a raised 6th. Making the notes A B C D E F♯ G♯. Still, every scale has one of each letter name.

You asked what you maybe thought was a simple question, but it's open a whole can of worms..!

I'm not talking pentatonics here, which are not diatonic scales!


I have an easy answer for this one that should guide you through most situations:

"if it seems weird using sharps, use flats. And vice versa".

For instance, say you're in "G#"

If you just write down the notes as you play them, you might do this:

G# A# C C# D# F G G#

Cleary no good. A scale (without getting eclectic here) needs seven differently lettered notes (C and C# are different notes, but they are both C).

So let's try it in sharps:

G# A# B# (this is weird!) C# D# E# (this is weird!) F## (this is super weird!) G#

Typically there's no such thing as "B#" (all respect to the Simpsons...remember the B#s...never mind). But to get seven notes, we have to take some artistic liberty.

Now let's try it in flats:

Ab. Bb, C, Db, Eb, F, G, Ab

So when somebody refers to a key as G#...and again, I've heard some compositional reasons for doing so that I never bothered to remember because they never matter to some poor old hack that went through the Berklee guitar program...if you were to write it down, you'd probably mean Ab.

  • Actually, this doesn't answer the question. It considers major while OP asks about minor, hardly explains why things might be weird, and your explanation of names in G# is quite convincing.
    – Tim
    Mar 10, 2020 at 9:07
  • The OP clearly states. "or any scale". I used G# because it is an ideal example (and qualifies as "any scale"). The OP also makes it clear they don't have a background in theory, so a practical-tip answer seems much more appropriate to me than a detailed theory treatise. In my experience, the majority of players appreciate this perspective, since the majority of players are not interested in the study of theory. Mar 10, 2020 at 12:01

There is a difference between learning the finger pattern and learning the notes in a given key. The former is very instrument specific (and tuning specific) while the latter is the same for all instruments.

There are only 7 letter names for notes in Western music and they are A, B, C, D, E, F, and G. They are repeated over and over.

The "natural" notes, i.e. no sharps or flats are the same as the letter names previously given. The Natural scale is C major and is C, D, E, F, G, A, B repeat.

This scale has the interval structure of w-w-h-w-w-w-h where w = whole, h = half. Notice that this is really a 3 interval pattern (w-w-h) repeated twice with a -w- step between them. The group (w-w-h) is a tetrachord (4 notes, 3 intervals).

On the guitar each fret spacing is a half step. So going from 2nd fret to 3rd is a half step up, going from 10th fret to 9th is a half down.

All scales, or modes, can be expressed in terms of -w- and -h- steps and -h-is one fret increase while -w- is two frets. This assumes the formula describes an ascending scale which is the standard. The natural minor scale is w-h-w-w-h-w-w. You can apply this starting at any fret. No need to refer to accidentals. The name of the note you start on is the name of that major scale. Same for Major scale with w-w-h-w-w-w-h. Start on Eb and you have the Eb major scale.

Now, if you want to figure out the correct way to write the scale in SMN, figure out the note names with accidentals, then there are a few more things to be aware of. (1) We don't mix flats and sharps in the same key. (2) We don't use jumps of a 3rd for consecutive notes. In other words all scales are a 7 letter string of the alphabet sequence (A, B, C, D, E, F, G, A, B, C, D, E, F, G, ...). So start with the first letter name, then write down the sequence of letters, now as you walk up the letters decide if the next letter represents the -w- or -h- you need and if not adjust it with a # or b respecting rule (1). That should work.

As an example try Eb minor. The starting note is Eb, letter name E. The sequence must be (Eb, F, G, A, B, C, D, Eb) and we need w-h-w-w-h-w-w. Next letter is F and F is 2 frets above Eb (a -w- step) so leave it alone. From F to G is a -w- and we need a -h- so put a "b" after G. Notice how we now have two flats. F# is enharmonic to Gb but the sequence (Eb, F, F#) would not be proper form. Now from Gb to A is three frets (a minor third) and we need a -w- so flatten it. So far (Eb, F, Gb, Ab, ...). Next letter is B and that is 3 frets from Ab so once again we flatten it to make a -w-, (Eb, F, Gb, Ab, Bb,...). Now we need a half step from Bb to a C and the interval between those notes is a -w-. So we much flatten the C, yes you heard right. That gives you (Eb, F, Gb, Ab, Bb, Cb, ...). So, why not just leave it a B natural? Again, not proper form, the scales are always an unbroken 7 letter subset of (A, B, C, D, E, F, G, A, B, C, D, E, F, G, ...) with no repeats. To finish it off we need a -w- from Cb to a D. There are 3 frets from Cb to D so we need to flatten D to fit the pattern giving

(Eb, F, Gb, Ab, Bb, Cb, Db, Eb) = Eb minor

There are 2 natural semitones in the key of C, (E, F) and (B, C). If you follow the rules you can figure out the scales.

For a guitarist one of the amazing things is the "movable" chord and scale patterns. I am not suggesting you don't learn to read as that is important, but the movable patterns are equally important. They allow you to change key on the fly while reading by moving to the appropriate location, all other patterns being equal. This is not the only skill to develop, one should also learn to play all keys in the same position. But at a moments notice you can read everything as if it were in C by moving the C-movable form to the correct location and simply reading the notes as if they were in C. Makes life very easy.

Not sure if you started learning these patterns but a popular minor scale fingering is

(1, 3, 4) on the E string

(1, 3, 4) on the A string

(1, 3, 4s) on the D string

(1, 3) on the G string

(1, 2, 4) on the B string

(1, 3, 4) on the high E string

The notation is as follows, you have 1 finger 1 fret from 4 consecutive frets at any location. Then just put the fingers down in the order listed. The 4s on the D string mean stretch and you need to reach for a -w- step there. This is not the only way to play the minor scale. Playing this starting on the 5th fret (standard tuning) would be A minor, 9th fret would be either Db minor or C# minor.


I'm adding to this to address Tim's comment on harmonic and melodic minor. The German H is not addressed. The algorithm above works for the diatonic modes, Ionian, Dorian, Phrygian, Lydian, Mixolydian, Aeolian (natural minor), and Locrian. And it works for figuring out key signatures. You will not find mixed accidentals in these scales or the key associated with them. Harmonic minor has a sharp 7th (relative to its natural state) and Melodic minor has a sharp 6th and 7th ascending and a natural 6th and 7th descending (again, relative to its natural state). These minor scales can be constructed from the natural minor by adding a # to the appropriate notes. And as Tim points out this will necessarily create a mix of flats and sharps in those scales. However, these are treated in SMN as accidentals. Music in the key of A minor may use melodic minor but you will not find a G# and/or F# in the key at the beginning of the piece. The key of A minor has no sharps or flats. There may be exceptions I am unaware of but I've not yet seen a harmonic or melodic minor key signature.

In the example I gave, building the Eb minor scale, the harmonic version would be (Eb, F, Gb, Ab, Bb, Cb, D, Eb). Still no mix of # and b. But G minor for example would be (G, A, Bb, C, D, Eb, F, G), and the harmonic minor version would be (G, A, Bb, C, D, Eb, F#, G).

  • With my 'picky' hat on, it must be pointed out that Western music includes German music. As such, another letter name pops up - H. Unfortunately it does throw a spanner in the works for questions (and answers) on this subject! And, we do mix # and b in the same key - in minors! Example - D harmonic minr - Bb and C#...
    – Tim
    Mar 10, 2020 at 9:11

As you're asking only about minor scales you seem to know how to play major scales.

So you play any major scale starting on the 6th degree: this will be its relative minor key (Aeolian mode). *1) e.g. C major scale -> 6th degree of C = A -> a minor -> A = root tone (1st degree)

mind that G - the 5th of C - is now the 7th of A!

Developing A harmonic minor: Now you will have to augment the 7th degree of this relative minor key to create a leading tone!

  • 7th degrees with a flat will need a natural sign:
  • 7th degrees that are natural will need a sharp: e.g. G = 7th of A -> G#
  • 7th degrees with a sharp wil need a double sharp

Developing the melodic relative scale:

same procedure as above with the seventh degree.



Eb major:

Eb F G Ab Bb C D Eb

6th degree is C -> C minor

C D Eb F G Ab Bb C -> 7th degree Bb becomes B natural -> C harmonic minor

melodic minor: 6th degree of C = Ab -> becomes A natural (7th stays B)



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