Harmonic Theory

Building Triads

A chord in it's simplest form is 3 or more notes. The most common variations of this basic harmony (triads) is a major triad, minor triad, diminished triad and augmented triad. Here are the degrees from the root that make up each of these triads (example in C):

Major Triad - 1 3 5 (C E G)

Minor Triad - 1 b3 5 (C Eb G)

Diminished Triad - 1 b3 b5 (C Eb Gb)

Augmented Triad - 1 3 #5 (C E G#)

To find these shapes on the neck, you need to know the interval between each of the notes that makes up the triad, and then be able to make those jumps on the fretboard. The interval structure of each of these triads are as follows:

(Major 3rd = 2 Whole Steps)

(Minor 3rd = 1 1/2 Steps)

Major Triad - M3 + m3

Minor Triad - m3 + M3

Dim Triad - m3 + m3

Aug Triad - M3 + M3

Here are some examples of these shapes on the fretboard:

Inversion: When the order of notes in a triad is changed.

Root, Third, Fifth (No Name)

Third, Fifth, Root (1st Inversion)

Fifth, Root, Third (2nd Inversion)

Harmonising Scales

You can harmonise a full scale just by using its notes to find the root, third and fifth of each degree. This involves a process of 'pick one, skip one, pick one, skip one, pick one'. For example, this is the process of harmonsing the major scale:

Major Scales Degrees: 1 2 3 4 5 6 7

C Major Scale: C D E F G A B

First Chord: Starts on first degree (i.e C).

C's 3rd and 5th (skip 2 and 4): E G

C E G = Major Triad

This means the first chord of a major scale is a major chord, in our example that's Cmaj.

Second Chord: Starts on second degree (i.e D).

D's 3rd and 5th in this scale (skipping 3 and 5): F A

D F A = Minor Triad

This means the second chord of a major scale is a minor chord. in our example, that's Dm.

If you did this for the rest of the major scale you would get:

1 = Major (1 3 5)

2 = Minor (2 4 6)

3 = Minor (3 5 7)

4 = Major (4 6 1)

5= Major (5 7 2)

6= Minor (6 1 3)

7 = Diminished (7 2 4)

So the chords of the C major scale are: C Dm Em F G Am Bdim 


If you were to follow the same process for the C minor scale, this would be the result:

Minor Scale Degrees: 1 2 b3 4 5 b6 b7

C Minor Scale: C D Eb F G G# Bb

Minor Scale Chords: 

1 = Minor (1 b3 5)

2 = Diminished (2 4 b6)

b3 = Major (b3 5 b7)

4 = Minor (4 b6 1)

5 = Minor (5 b7 2)

b6 = Major (b6 1 b3)

b7 = Major (b7 2 4)

So the chords of the C minor scale are: Cm Ddmin Eb Fm Gm G# Bb

Relative Theory

As you may have noticed, when you look at the chord scale for the major and minor scale, the chords themselves are in the same order, just starting on a different note. That's due to relative theory. Every major key has a relative minor key, that is, a minor scale that contains all the same notes, and vice versa. Here's how:

C Major Scale Notes

 1   2   3   4   5  6   7

C  D  E  F  G  A  B

If you started that scale on the 6th degree you would get this:

6  7   1    2   3  4   5

A  B  C  D  E  F  G

Which actually is the A Minor Scale:

1   2  b3 4   5  b6 b7

A  B  C  D  E  F  G

You may also notice here that C, which was our root initially, is now the b3 of A Minor, and therein lies the relative theory basics:

The Sixth Degree of a major scale is the root of its Relative Minor

The b3 of a minor scale is the root of its Relative Major

That means both C major and A minor contain the same notes and chords, just in a different order as the root has been shifted. Here are all the relative Majors to Minor (of course, they also work the other way):


C Major - A Minor

C# Major - Bb Minor

D Major - B Minor

D# Major - C Minor

E Major - C# Minor

F Major - D Minor

F# Major - D# Minor

G Major - E Minor

G# Major - F Minor

A Major - F# Minor

Bb Major - G Minor

B Major - G# Minor

Seventh Chords

A Seventh Chord is created by adding another 3rd to an existing triad.

Major 7 = 1 3 5 7 (R M m M)

Minor 7 = 1 b3 5 b7 (R m M m)

Dom 7 = 1 3 5 b7 (R M m m)

Major Key 7th Harmony: Maj7, min7, min7, Maj7, Dom7, min7, m7b5

Minor Key 7th Harmony: min7, m7b5, Maj7, min7, min7, Maj7, Maj7

Extended Chords

Extended chords are formed by adding notes from the second octave of a chord that are outside of the triad being used. The naming of these chords is derived from the naming of 7th chords i.e a Maj7 chord with a 9th added would be a Maj9 chord, as the 7th is implied.

Degrees: 9 (2), 11 (4), 13 (6).

Chord Formulas:

Maj9: 1 3 5 7 9

m9: 1 b3 5 b7 9

Dom9: 1 3 5 b7 9

Maj11: 1 3 5 7 11

m11: 1 b3 5 b7 11

Dom11: 1 3 5 b7 11

Maj13: 1 3 5 7 13

m13: 1 b3 5 b7 13

Dom13: 1 3 5 b7 13

Parallel Keys

Parallel keys are two different keys (i.e major and minor) that have the same root. For example, G Major and G Minor, A Minor and A Lydian etc.

Parallel keys can be used to incorporate tones and sounds in progressions that wouldn't normally be found in the key. Example:

- We are playing in Dm, which has the degrees 1 2 b3 4 5 b6 b7, but we want to include the natural 7th degree. This degree (a C# note) is found in the parallel key D Major (1 2 3 4 5 6 7).

- We need to figure out which chords in the key of D Major contain the 7th degree so we can choose which sound best to bring into our Dm progression.

- Every degree in the scale is part of the chords in the key (it's the 1st, 3rd and 5th of a chord). The 7th degree is the root of the 7th chord, 3rd of the 5th chord, and 5th of the 3rd chord.

- Therefore we can bring in C#dim(7th), Amaj(5th) and F#m(3rd) into our Dm progression to include that 7th degree. Example progressions:

- Dm C#dim C Bb

- Dm F Bb A

Chord Substitutions

Substituting a chord is the process of replacing an existing chord in a progression for one that has a similar function but a different sound. There are multiple different ways to choose a new chord to replace one you have, but these are the most common and useful:

1) Relative chords (minor to major or vice versa. i.e replacing a full two bars of C major with one bar of C major and one bar of Am7)

2) Chords that contain the melody note (every note in a key is found within at least 3 chords because every chord is built from three notes in the key. Therefore in the key of C, if the melody note is a C note, you could swap just using the root chord (CEG) with the vi chord (ACE) or the IV chord (FAC).

3) Changing the Dominant Chord (i.e G7 in a Cmaj progression) for it's fifth as a minor chord. This would result in this rule: V can be replaced with ii in a major key. bVII can be replaced with iv in a minor key.

You can also adapt your basic chords (major, minor and dominant) for other chords of a similar harmony. Eg:

Major - maj7, maj6, sus2, sus4, add9 etc

Minor - min7, min6, sus2, sus4, add9 etc

Dominant - ANY dominant chord

Complete Chord Chart

Complete Modal Chart