Western music theory is littered with jargon and turns of terminology that can often be confounding and confusing, which itself is spurred on a great deal by the ambiguities inherent in Western languages, English in particular. Take ‘Minor Key Signatures’, for example, which you would be forgiven for thinking is going to be an article about the autographic calligraphy of some new rapper called Minor Key.
What has this to do with the guitar music that you so yearn to master? Well, apart from everything, not all that much, only the very code that makes up some of your favorite songs, not to mention the key to cracking on with your own compositions and improvisations!
Table of Contents
- What Exactly is a Minor Key?
- How Best to Calculate These Scales for Yourself?
- When Exactly is a Key Minor?
- What is a Key Signature?
- Parallel Keys
- Relative Keys
- Final Tones
- FAQs
So yes, if you are theoretically inclined this couldn’t be more vital, and even if you aren’t there will doubtless be plenty for you to sink your teeth and mind into, to enhance and amplify your guitar studies or simply to understand better the logistics and inherent logic of Western compositions.
For these are matters of music that, while focused on guitar today, are universal in the West and thus will enable you to communicate on an astute level with musicians of all varieties, transposing or not, woodwind or sax, piano or brass.
And since this theoretical language is more often than not removed from nationalised language forms, this is a language that will enable you to cross boundaries, through music styles and cultures, engaging as you might in cross-cultural exchange between citizens of other countries throughout the Western hemisphere and even some in the East.

What Exactly is a Minor Key?
Just as there are major keys, so too there are minor keys, and just as these major keys are so called because of their being comprised of notes from the corresponding diatonic major scale, the same goes for a minor key. The terminology we use to describe the two remains almost entirely the same, certainly in terms of scale degrees, apart from one small difference:
Major Scale Degrees | Tonic (I) | Supertonic (ii) | Mediant (iii) | Subdominant (IV) | Dominant (V) | Submediant (vi) | Leading Tone (vii) | Tonic (octave) (I) |
Minor Scale Degrees | Tonic (I) | Supertonic (ii) | Mediant (iii) | Subdominant (IV) | Dominant (V) | Submediant (vi) | Subtonic (vii) | Tonic (octave) (I) |
Those with a keen eye will have spotted that this one difference lies in the seventh scale degree. A leading tone, as in the major scale, describes a note preceding or following another by one semitone. This, of course, doesn’t apply to the minor scale, certainly not the natural minor, whose seventh scale degree is inherently minor, thus having two semitones to travel in returning to the tonic.
The numbers themselves are unchanged, as with all scales to a degree. However, the gaps between the numbers in terms of what they represent on an actual scale vary wildly depending on which scale is being played or referred to.
The same example, of major and minor scale degrees, can be seen in action with the C major and C minor scales placed side by side:
Scale Degree | Tonic (I) | Supertonic (ii) | Mediant (iii) | Subdominant (IV) | Dominant (V) | Submediant (vi) | Leading Tone (vii) | Tonic (octave) (I) |
Note | C | D | E | F | G | A | B | C |
Scale Degree | Tonic (I) | Supertonic (ii) | Mediant (iii) | Subdominant (IV) | Dominant (V) | Submediant (vi) | Subtonic (vii) | Tonic (octave) (I) |
Note | C | D | Eb | F | G | Ab | Bb | C |
So, though these scales share several of the same notes and begin on the same tonic, they are in fact very different as a result of their key differences from each other, namely the Minor (flattened) 3rd, Minor (flattened) 6th, and the Minor (flattened) 7th.
How Best to Calculate These Scales for Yourself?
If all of these numbers are overwhelming at first, then have no fear! For there are plenty of other ways to approach this vital cornerstone of Western music, and if you follow them right with respect to your own strengths and weaknesses you will be a master in no time.
One such method is the use of formulas, very valuable in initially sussing out scales and working them out for oneself. All scales can be calculated in this way, dissected into segments of Half, semitones (one fret), and Whole, tones (two frets), and the minor and major scales are no exception. See if you can spot the differences between these two examples in C major and C minor:
Note | C | D | E | F | G | A | B |
Steps (from previous) | Half (1 fret) | Whole (2 frets) | Whole (2 frets) | Half (1 fret) | Whole (2 frets) | Whole (2 frets) | Whole (2 frets) |
Note | C | D | Eb | F | G | Ab | Bb |
Steps (from previous) | Whole (2 frets) | Whole (2 frets) | Half (1 frets) | Whole (2 frets) | Whole (2 frets) | Half (1 frets) | Whole (2 frets) |

When Exactly is a Key Minor?
A piece of music, or a section of a piece of music for that matter, is said to be in a minor key if it is mainly centred on the notes of a given minor scale with a particular emphasis on the tonic of the given scale. This classification is much like its major scale brethren, exactly the same in fact, and goes for all scales and types of key.
We say ‘mainly centred on the notes of a given minor scale’ because it is okay for a song to use notes other than those specified in the given key at the given time. Where would we be without dissonance, for example?
This brings us to one of the major differences between the major and minor scale, besides their inherent differences in expressively tonal qualities. The minor scale, unlike its major scale relative, occupied and exists in several different permutations, the most simple and relatable to the major scale being the natural minor scale.
The harmonic minor scale, for instance, is constructed by taking the corresponding natural minor scale and augmenting (sharpening or raising) the seventh degree so that it is now a major 7th, a leading tone. This is still the same key but would require, in musical notation, the use of an accidental in the key signature.
What is a Key Signature?
As with major keys, minor keys are represented on a musical stave with a Key Signature.
At its simplest, a key signature is simply a code with which a musician might instantaneously assess what key song is in.
Their implementation in musical contexts comes from a desire to remove at least some, if not a large majority, of the marks and symbols beside individual notes when sharpening or flattening them.
Thus, the key signature comes as a way to bypass the inherent inadequacy of any kind of musical notation, even that so grandiosely used to represent the so called pinnacle of Western artistic achievement in music.
All of these key signatures are the same as major key signatures, illustrated in exactly the same way, and with each of the sharps or flats placed on the notes of the stave that are sharpened or flattened by the corresponding key.
Sharps
The sharps, designated thus, outline the following minor keys, so detailed for having this number of sharps in each key signature:
- 0 – A minor
- # – E minor
- ## – B minor
- ### – F# minor
- #### – C# minor
- ##### – G# minor
- ###### – D# minor
- ####### – A# minor
Flats
The flats, designated thus, outline the following minor keys, so detailed for having this number of flats in each key signature:
- 0 – A minor
- b – D minor
- bb – G minor
- bbb – C minor
- bbbb – F minor
- bbbbb – Bb minor
- bbbbbb – Eb minor
- bbbbbbb – Ab minor
Parallel Keys
A parallel key, much like its etymological namesake, is a key that runs in tandem with another, in this case its minor/minor mirror image. Each major/minor scale has a minor/scale parallel key inherently, and vice versa.
C minor, for example, is the parallel minor of C major, and the opposite is true for C major being the parallel major of C minor:
Scale Degree | Tonic (I) | Supertonic (ii) | Mediant (iii) | Subdominant (IV) | Dominant (V) | Submediant (vi) | Leading Tone (vii) | Tonic (octave) (I) |
Note | C | D | E | F | G | A | B | C |
Scale Degree | Tonic (I) | Supertonic (ii) | Mediant (iii) | Subdominant (IV) | Dominant (V) | Submediant (vi) | Subtonic (vii) | Tonic (octave) (I) |
Note | C | D | Eb | F | G | Ab | Bb | C |
Both share a root note which, as discussed above, is a vital part of the classification of a key, needing to orbit around this central tonic note more often than not to be classified thus. Both C major and C minor also share the 2nd, 4th, and 5th scale degrees, the latter two being vital tones with which many Western compositions are harmonically formed, whether in classical spheres or among more popular circles.
For these similarities, even the average listener who doesn’t have much, if any, knowledge of music theory, can discern that both the major and parallel minor versions of the same key are in some way related.
However, the differences between them aren’t to be ignored! The 3rd, 6th, and 7th scale degrees having been flattened into minor versions of themselves, the overall character of this minor version of the key is radically altered, much like the corresponding key signature. Whereas C major is devoid of markings in its key signature, the key of C minor is punctuated by three flats, Eb, Ab, & Bb.
Relative Keys
So, it ought to be obvious that parallel keys have a pretty strong bond between them. However, nothing can quite compare to the relationship between a major and its relative minor, nor to a minor and its relative major. They are so close to each other as to use the exact same notes and key signature!
But if, as outlined above, a minor and major key are so inherently different then how can it be that they share the exact same notes?
Well, unlike the parallel keys, they don’t share the same root note. More exactly, the relative minor of a major key will come from the using the 6th scale degree as the tonic, and the relative major of a minor key from the 3rd degree of the corresponding scale.
We will, again, use the example of C minor to get the point across, alongside its relative major, Eb:
Scale Degree | Tonic (I) | Supertonic (ii) | Mediant (iii) | Subdominant (IV) | Dominant (V) | Submediant (vi) | Subtonic (vii) |
Note | C | D | Eb | F | G | Ab | Bb |
Steps (from previous) | Whole (2 frets) | Whole (2 frets) | Half (1 fret) | Whole (2 frets) | Whole (2 frets) | Half (1 fret) | Whole (2 frets) |
Scale Degree | Tonic (I) | Supertonic (ii) | Mediant (iii) | Subdominant (IV) | Dominant (V) | Submediant (vi) | Leading Tone (vii) |
Note | Eb | F | G | Ab | Bb | C | D |
Steps (from previous) | Half (1 fret) | Whole (2 frets) | Whole (2 frets) | Half (1 fret) | Whole (2 frets) | Whole (2 frets) | Whole (2 frets) |
With the respective tonic of each other highlighted above, it ought to be fairly straightforward to see that both are entirely related, merely shifted along a couple of steps, misaligned if you will, which stops them from being ‘parallel’.
Final Tones
Any one can formulate a minor scale if they know the root note and trace it through the following formula:
Whole (2 frets) – Half (1 fret) – Whole (2 frets) – Whole (2 frets) – Half (1 fret) – Whole (2 frets) – Whole (2 frets).
And, as the guitar is so ripe for transpositions – being so structured as to welcome moving up and down the fretboard with ease if you know the numbers – then you can map out your favorite scale wherever you so wish.
A fun exercise might be to place a minor scale shape at random on the fretboard, and then to see if you can use your ear alongside the learning today to suss out the rest of the notes, starting from the root note, typically on the bottom E or A string, and working onwards.
FAQs
If you aren’t immediately able to discern this by ear, then the easiest way to tell is to listen out for the major 3rd, which itself is very common in lots of blues-oriented rock music. Theoretically, a key is minor (natural minor, that is) if its 3rd, 6th, and 7th scale degrees are flattened and made minor. A major key will not feature any alterations like this. However, each key signature is both major and minor, depending on the root from which it is deducted.
To calculate the minor scale from a key signature, one would take the sixth scale degree of the major as the tonic and ascend by steps like so, with Whole equating to 2 frets and Half to 1: Whole – Whole – Half – Whole – Whole – Half – Whole.
Unlike the major scale, there are several permutations of the minor scale, the Natural Minor most closely aligning with the intention of the major scale equivalent. The other most common minor scales are the Harmonic Minor, which simply augments (sharpens) the sixth scale degree to a Major 7th, and the Melodic Minor ascending simply flattens the 3rd of the Natural Minor, while descending it flattens the 3rd, the 6th, and the 7th.