Understanding guitar scales: Guitar scales explained

Ever wondered what scales are and why they are so important for guitarists? In the following article we’re going to answer some of the most common questions around the topic of guitar scales including:

  • What scales are
  • Why scales are important for guitarists
  • The different types of scales
  • Step patterns and formulas
  • Scale patterns and how to read scale diagrams
  • Which scales guitarists should learn

This article is the second of a series on basic music theory for guitarists. If you haven’t read the first article on ‘How to learn all notes on guitar’ I’d recommend starting there and then coming back.

Key Points

Scales are any set of notes ordered by pitch. The major scale is the most fundamental and is used in comparison to define all other scales. Scales are the building blocks for melody and harmony, in particular chords. Understanding step patterns and scale formulas is key to understanding scales and their role in music. Guitarists are advised to learn the major, minor, major pentatonic, minor pentatonic and blues scale when first learning scales.

What are scales?

Scales are any set of notes ordered by pitch.

Scales are a fundamental aspect of music theory, and while music theory can appear complicated, scales simply consist of any set of notes, provided they are arranged in order of pitch e.g. from low to high (ascending scale) or high to low (descending scale), generally within a given octave and then repeating the same pattern in all octaves.

Another way of interpreting scales would be to consider them as defining how an octave is divided into steps.

The Chromatic Scale

Western music consists of 12 notes:

The Chromatic Scale
A, A♯, B, C, C♯, D, D♯, E, F, F♯, G, G♯

When these 12 notes are assembled in order of pitch they form the chromatic scale, also referred to as the 12 tone scale.

Tonic

The first note the scale begins on is known as the tonic and defines the key (in fact it’s also referred to as the ‘key’ note) of the scale. For example if you play the chromatic scale as per the example below:

B Chromatic Scale
B, C, C♯, D, D♯, E, F, F♯, G, G♯, A, A♯

You would be playing the B chromatic scale. If you started a half step up on the C you would be playing the C chromatic scale.

C Chromatic Scale
C, C♯, D, D♯, E, F, F♯, G, G♯, A, A♯, B
 If you are unfamiliar with the chromatic scale, sharps and flats and how to locate notes on the guitar fretboard, I’d recommend reading our article on how to learn all notes on guitar

It can be useful to think of the tonic as the note the other notes revolve around. Our ears have an expectation that the scale will resolve or keep coming back to the tonic.

Why Learn Scales?

There’s two reasons guitarists should understand and practice scales.

Firstly, there’s music theory.

If you understand how specific notes relate to one another and how this relates to chords and chord progressions you will have a better understanding of the guitar, and this will be useful when it comes to improvisation, developing your ear e.g. recognising notes and intervals (spaces between notes), songwriting, and communicating with other musicians.

Secondly, scales are useful for building muscle memory and finger dexterity and over time will be the backbone of developing good single note technique and ultimately speed.

Types of Scales

Because the chromatic scale includes every available note in the western music system it’s rarely used in a practical sense. This is because by not leaving out any notes it lacks a structure, and as guitarists we know it is often the notes we leave out that define the music we are playing.

A better way to look at the Chromatic scale is to consider it a scale that can be used to build other scales, with this in mind it can be useful to consider the chromatic scale as the ‘musical alphabet’.

In the spoken and written word, we extract letters from the alphabet to form words and sentences to communicate ideas.

In music, the ‘musical alphabet’ is the chromatic scale, and notes can be extracted from it to create other scales which can then be used to create musical ideas in the form of melody (single notes) or harmony (chords).

chromatic to major scale

There are many different types of scales, and within each category of scale, different subcategories exist. We can break them into the following categories:

 

Scale name Notes per octave
Chromatic 12
Octatonic 8
Heptatonic 7
Hexatonic 6
Pentatonic 5
Tetratonic 4
Tritonic 3
Diatonic 2
Monotonic 1

Most of the scales relevant to guitarists consist of between 5 (Pentatonic) and 8 (Octonic) notes, with 7 (Heptatonic) being the most commonly used. For example, both the major and minor scales are Heptonic.

Diatonic Scales

Diatonic scales refer to the construction of a specific type of scale rather than as a scale itself.

For example, diatonic scales are 7 note scales (Heptonic) that contain 5 whole notes and 2 half notes, with the two half notes being separated by 2-3 whole steps. In this way they are built upon the intervals of natural notes with each successive note being a perfect fifth of the note before it.

This doesn’t mean diatonic scales don’t contain accidentals just because they are built on the intervals of natural notes, it depends on the tonic e.g. the G major scale is a diatonic scale and includes an F♯ as the seventh note of the scale.

Major scales are diatonic scales, as they contain 5 whole notes, 2 half notes and the 2 half notes are separated by 2 whole steps.

Step Patterns and Formulas

We can read scales in one of two ways, either by the step pattern or by the scale formula.

Step Patterns

Step patterns refer to the order of whole and half steps in a given scale, written as ‘W’ for whole step and ‘H’ for half step. As guitarists we can think of steps as frets e.g. a half step is equal to 1 fret, a whole step is equal to 2 frets.

A practical example of this is the major scale which is as follows:

Major scale step pattern
W – W – H – W – W – W – H

For instance the A major scale consists of the following steps (repeating on the A an octave higher):

Scale Step Patterns

Scale Formulas

Scale formulas use numbers to compare to specific notes of the major scale. You may have heard other guitarists refer to the 3rd or 5th when discussing harmony or chord formations, these are just the 3rd and 5th notes of the major scale respectively.

To put it simply, scale formulas tells us which notes of a scale in the same key are different to the notes of the major scale (the major scale being the most important scale) and if they are higher or lower in pitch.

For example, the formula for the major scale is: 1, 2, 3, 4, 5, 6, 7

We’ll use the C major scale as an example, as it is a scale that contains all natural notes e.g. no sharps or flats:

1 2 3 4 5 6 7
C D E F G A B

The formula for the minor scale is: 1, 2, ♭3, 4, 5, 6, ♭7

Knowing what we now know about scale formulas, we can build a minor scale from a major scale by flattening the 3rd, 6th and 7th notes of the scale.

Major Formula 1 2 3 4 5 6 7
Minor Formula 1 2 ♭3 4 5 6 ♭7
Major Notes C D E F G A B
Minor Notes C D ♭E F G ♭A ♭B

As demonstrated in the table above, we have flattened the 3rd, 6th and 7th notes of the C major scale to form the C minor scale.

Major Scale 1 2 3 4 5 6 7
Minor Scale 1 2 ♭3 4 5 6 ♭7
Major Pentatonic 1 2 3 5 6
Mino rPentatonic 1 ♭3 4 5 ♭7
Blues Scale 1 ♭3 4 ♭5 5 ♭7
 * Remember not all scales contain 7 notes. 
Why do you see flats and sharps written before and after natural note names?
When composing music the accidental (the sharp or flat note) is written before the note. When simply written down or spoken we say the name of the note first followed by the sharp or flat.
Why does the C Major scale contain no sharps or flats?
As we know from discussing step patterns, the major scale consists of the following step patterns and corresponding notes:

W W H W W W H
C D E F G A B

Scale Patterns

You have probably seen a scale diagram before.

They are similar to chord diagrams, and simple to understand once you know how they are laid out.

In the diagram below the scale diagram is shown in horizontal format and like most scale diagrams covers two octaves.

You will also see scale diagrams in vertical format at times, however the same rules still apply.

G Major Scale

G Major Scale

Firstly, scale diagrams contain 6 horizontal lines with each line representing a guitar string, with the bass notes on the bottom and treble notes at the top. In the case of a vertical scale diagram the low E will be displayed as the line furthest to the left.

The lines running vertically represent the frets, again this will be shown horizontally if in vertical format.

The dots represent the notes that make up the scale. The black dots show the tonic, often referred to as the root note. Although technically the tonic and root note can, and often are the same note, technically the two terms indicate different things.

What’s the difference between the Tonic and Root Note?
The tonic refers to melody, root refers to chords. They are often the same but the two terms mean different things. For instance the tonic is the note a melody or section of a melody resolves on, some people refer to this as the ‘home note’ and our ears come to expect the melody to resolve on this note or keep coming back to this note. The root is simply the first degree of a chord e.g. The first degree of a C chord is ‘C’.

Some scale patterns also include numbers representing fingers as the suggested finger to use to play the specific note.

Keep in mind, there are as many ways to play scales as there are chords, depending if you prefer to stay within a fixed position (caged system) or want to play higher up the neck (3 notes per string method).

The Caged System

The caged system takes its name from the fact that it utilises 5 open major chord shapes: C, A, G, E and D which can then be moved up or down the neck to create different chords, provided the index finger is positioned where the nut would otherwise be.

The caged system is a way of visualising chords and scales using set patterns contained within a 4 fret position (occasionally 5) that can be moved up or down the neck changing the chord or tonic of the scale being played. If you incorporate barre chords into your playing, you are already using the CAGED system to play chords.

For example, if you play an open A chord shape on the 4th fret while barring the 2nd fret with your index finger you are now playing a B chord.

The CAGED system is useful because it can help unlock the guitar neck, and allows you to do a great deal with basic moveable shapes.

I’ll cover the CAGED system in detail in a future article but for the purpose of understanding how it relates to scales, it’s important to know the scale patterns utilised fit closely to the corresponding chord shapes, making it simpler to visualise how these relate to each other.

The patterns will also be contained within 4 frets with one finger assigned to each fret and each pattern can be moved, which changes the key of the scale.

For instance, the scale diagram we used earlier for the G major scale can be transposed to the A major scale simply by moving the entire pattern a whole step (2 frets) higher up the neck.

A Major Scale – Caged System

A Major Scale - Caged System

We’ll be using the CAGED system to demonstrate scale patterns for the remainder of this article as it makes a good starting point for beginners new to music theory, but other patterns including the ‘three notes per string method’ are also widely used.

Three Notes per String

As the name implies, this system incorporates three notes per string. Its main benefit is it allows the guitarist to extend past just the two octaves the CAGED system allows for.

G Major Scale – 3 Notes per string

A Major Scale - 3 Notes Per String

It’s up to you which method you use. For beginners I’d recommend the CAGED system as this will make the most sense visually in how it relates to chords.

The three note per string system is better for more advanced players who want to utilise the length of the neck in their lead playing and their fingers are more adjusted to the longer stretches required.

Which scales guitarists should learn?

There are 5 scales every guitarist should learn to begin with, these are:

  • The Major Scale
  • The Natural Minor Scale
  • The Major Pentatonic Scale
  • The Minor Pentatonic Scale
  • The Blues Scale

I’ve provided scale diagrams for each below. For the sake of consistency I’ve listed all scales in the key of G but all patterns used are movable and the tonic of the scale is always the first note listed.

The Major Scale

If you are interested in music theory in any capacity, the major scale is the first scale you should learn as it is the most important scale in music. It consists of 7 notes in total and uses the following note intervals:

Major scale step pattern
W – W – H – W – W – W – H

If you recall the section on ‘Step Patterns’ this should begin to make sense. Remember, regardless of where you shift the pattern the intervals remain the same.

G Major Scale

G Major Scale

The Natural Minor Scale

The natural minor scale is often referred to as simply the ‘minor scale’ or ‘aeolian mode’ (we’ll cover modes in a future article). Understanding the minor scale will allow will help you build other minor scale including the harmonic minor scale.

The minor scale also contains 7 notes (Heptatonic) but differs in the fact that the 3rd, 6th and 7th steps are flattened by one semitone or fret on the guitar.

Major scale step pattern
W – H – W – W – H – W – W

G Minor Scale

G Minor Scale

The Major Pentatonic Scale

Unlike the major and minor scales which contain 7 notes, Pentatonic scales utilise 5 notes per scale. We already know ‘tonic’ refers to the key note of the scale (tone). Penta in Greek means 5, hence Pentatonic refers to a ‘5 note scale’.

Penta (5) + Tonic (note) = 5 note scale

The difference between the major scale and the major pentatonic scale is the removal of the 4th and 7th notes of the scale.

Pentatonic scales are synonymous with rock and country and would have to be the most played of all scales for guitarists.

Removing the two notes (4th and 7th) removes the half steps and as a result more dissonant (disharmonious) intervals of the major scale. As a result the major pentatonic scale is considered more versatile.

Major pentatonic Scale step pattern
W – W – W + H – W – W + H

G Major Pentatonic Scale

G Major Pentatonic

The Minor Pentatonic Scale

Just as the major pentatonic scale contains 5 notes from the major scale, the minor pentatonic scale contains 5 notes from the minor scale, leaving out the 2nd and 6th notes respectively. The minor pentatonic can be heard throughout rock and blues.

Minor pentatonic scale step pattern
W – W – H – W – W – W – H

G Minor Pentatonic Scale

Minor Pentatonic Scale

The Blues Scale

The blues scale utilises 6 notes (hexatonic) and is almost identical to the minor pentatonic scale, with the addition of the ‘blue note’ or diminished 5th.

As the name implies it works particularly well over 12 bar blues chord progressions.

Blues scale step pattern
W + H – W – H – H – W + H – W

The Blues Scale

The Blues Scale

Summary

I hope the information above helps explain exactly what scales are and why they are so important for guitarists for both gaining an understanding of the fretboard along with building finger dexterity through practice.

We’ll cover the topic of scales in more detail in coming articles including, the use of alternate picking to practice scales, some of the different scale patterns available and modes and how they relate to scales.

In the meantime if you have a question or something to add why not leave a comment below and share your thoughts with the rest of our readers.

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