Chord substitution is a technique used by improvisers and composers. In this technique, one or more chords in a chord progression are replaced by other, seemingly different chords.
This is because some chords share certain qualities with other chords, which make them interchangeable under certain circumstances despite having different root notes and sounding very different.
There are many ways to substitute chords! And we will examine some of the more common ways jazz players utilize chord substitutions. We’ll discuss:
- Tritone Substitution
- Secondary Dominant Chords
- Modal Interchange and Borrowed Chords
- And Many Others
So, let’s explore different types of chord substitutions and explain why they work the way they do!
This article is a great starting point to learn how chord substitutions work in music theory. However, if you want a deeper dive into what makes a chord substitution work, check out the Learn Jazz Standards Inner Circle.
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Table of Contents
What is a Chord Substitution?
Here is the simplest definition for chord substitution:
- A chord substitution is a musical technique where an original chord is swapped out for another chord that
- Chord substitutions work because they often have the same (or nearly the same) harmonic function as the original chord, share the same common tones, or produce smooth voice leading that resolves the progression in a way that is similar to the original chord and sounds good.
- The substituted chord often provides new and creative harmonic interest while maintaining the original chord progression’s momentum and function.
This technique is widely used in many music genres, including classical and popular music, to add variety and complexity to the harmony. However, it is most commonly used in jazz music.
Why Learn About Chord Substitutions?
Don’t think you need to know anything about chord substitutions?
Well, whether or not you are a chordal player, you still need to understand chord substitutions because they are a fundamental part of jazz language and the jazz style.
When you learn certain jazz songs, you are learning various chord substitutions, whether you know it or not.
What’s more, the harmonic concepts behind chord substitutions are widely used by jazz improvisers during jazz solos, even when there isn’t necessarily a chord substitution played by the chord player.
Don’t believe me? Check out this line:
A line like this one implies a tritone substitution over the dominant chord.
A tritone substitution is one of the many types of chord substitutions we will explore later in this article. Lines like this reveal that your improvisational options are greatly expanded if you know how to imply chord substitutions in your solos.
The Importance of Learning Jazz Chord Progressions Before Practicing Chord Substitutions
It’s important for musicians studying jazz to know some of the common jazz chord progressions that you will encounter in jazz standards. To understand jazz chord progressions, you first need to understand diatonic chords and the progressions you can build from them.
Chord families are groups of chords that are built from the same scale. We will use the major scale as our example. When you use the major scale to construct diatonic chords, you end up with the C major chord family, which includes:
- C major chord (C chord)
- D minor chord (Dm chord)
- E minor chord (Em chord)
- F major chord (F chord)
- G major chord (G chord)
- A minor chord (Am chord)
- B diminished chord (Bdim chord)
Let’s build a C chord from the C major scale:
When going through this process for each note in the scale, we end up with the seven diatonic chords mentioned above:
Diatonic chord progressions are built from these seven diatonic chords. Here are some below:
ii-V-I Chord Progression in C
I-vi-ii-V Chord Progression in C
IV-V-iii-vi Chord Progression in C
By learning the most common progressions, which often include chord substitutions written into the harmony, you’ll have a serious leg up on learning jazz songs and getting your jazz improvisation together.
Check out this crash course on nine jazz chord progressions you need to know.
5 Different Types of Chord Substitutions
Without further ado, let’s learn some chord substitutions!
Here are five types of chord substitutions jazz players will use when comping/improvising or jazz composers will write into their chord progressions:
Diatonic Substitutions
This chord substitution occurs when a chord is replaced by another chord from the same key. Chord families are built from the same seven notes. Therefore, chords built off of adjacent thirds will share many of the same notes.
For example, in the key of C major, you might replace a C major chord (or the tonic chord) with an A minor chord because both chords share some of the same notes (C and E):
C major
- 5th: G
- 3rd: E
- Rt: C
A minor
- 5th: E
- 3rd: C
- Rt: A
It’s called a relative minor or relative major chord substitution when you substitute the tonic major chord for its relative minor or vice versa. The relative minor key shares the same key signature and, therefore, the same chords as the major keys.
So, in a progression, a major chord can be replaced with its relative minor or vice versa. For example, in C major, you could replace the tonic chord, or C major, with A minor, the tonic chord the relative minor key.
You can also substitute C major with E minor because they also share two of the same notes:
C Major
- 5th: G
- 3rd: E
- Rt: C
E Minor
- 5th: B
- 3rd: G
- Rt. E
If you have a keen eye, you’ll notice that an A minor triad, when added to a C major triad, creates an A-7 chord.
A-7
- 7th: G
- 5th: E
- 3rd: C
- Rt: A
Likewise, a C major triad, when added to an E minor triad, creates a Cmaj7 chord.
Cmaj7
- 7th: B
- 5th: G
- 3rd: E
- Rt: C
This chord logic also applies to seventh chords and extended chords.
A-7 and Cmaj7 share many of the same notes, just like A- and C do.
A-9
- 9th: B
- 7th: G
- 5th: E
- 3rd: C
- Rt: A
Cmaj7 and E-7 chords share many of the same notes, just like a C triad and an Eminor triad share many of the same notes.
Cmaj9
- 9th: D
- 7th: B
- 5th: G
- 3rd: E
- Rt: C
How Diatonic Chord Substitutions Appear in Chord Progressions
Here, the I chord (C) was switched out for a iii chord (E-). As mentioned above, the I chord and iii chord share many of the same notes. It is quite common for a I-vi-ii-V chord progression to be played as a iii-vi-ii-V.
Let’s look at another example. A D-7 and Fmaj7 share many of the same notes because they are built from adjacent thirds (much like Cmaj7 and E-7, or A-7 and Cmaj7). Playing an Fmaj7 over a D-7 chord implies chord extensions (the 9th).
D-7
- 7th: C
- 5th: A
- 3rd: F
- Rt: D
Fmaj7
- 7th: E
- 5th: C
- 3rd: A
- Rt: F
If we replace the ii chord with a IV chord, we imply a rootless D-9 chord instead of a regular ii chord. The substitute chord has all the same common tones (except for the D).
This is one way to change the sound of this common chord progression and make it more interesting without sacrificing its harmonic function.
Applying Diatonic Substitutions in Your Jazz Solos
When improvising, using diatonic substitutions can help you imply chord extensions. Let’s explore a few examples.
If the chord on the lead sheet is Cmaj7, but you outline an A minor chord substitution, you are implying a C6 chord:
If you play an E-7 over a Cmaj7 chord, you are outlining a Cmaj9 chord:
BEFORE YOU CONTINUE...
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Tritone Substitution
The tritone sub is a common chord substitution technique in jazz and one we briefly referenced in an earlier section. This type of chord substitution occurs when a dominant seventh chord is replaced by another dominant seventh chord, one tritone interval (three whole steps) away.
This is how this chord substitution works. A dominant chord a tritone interval away shares the same guide tones as the original chord.
Guide tones are the 3rd and the 7th in any chord. These important chord tones provide important information regarding the harmonic movement in a chord progression. Here are the guide tones in a G7 chord and its tritone substitution, Db7.
Notice how they are the same!
G7
- 7th: F
- 5th: D
- 3rd: B (Cb)
- Rt: G
Db7
- 7th: Cb (B)
- 5th: Ab
- 3rd: F
- Rt: Db7
So, the V7 in a ii-V-I chord progression can be substituted with the bII7 chord because these two chords share the same guide tones. Let’s see that process in action!
Here is how the notes move in a regular ii-V-I progression in C:
- C moves to B. Then, B stays on B.
- A moves to G. Then, G stays on G.
- F stays on F. Then, F moves to E.
- D stays on D. Then, D moves to C.
Now, let’s examine the harmonic movement when we replace the G7 with a tritone substitution (Db7):
- C moves to Cb. Then, Cb stays on Cb (B).
- A moves to Ab. Then, Ab moves to G.
- F stays on F. Then, F moves to E.
- D moves to Db. Then, Db moves to C.
As you can see, the tritone substitution maintains the guide tones of the original chord while adding chromatic movement in the bass note and the fifth.
Therefore, despite a different root note, the harmonic function of the two chords remains the same.
Tritone Substitutions in Chord Progressions
The most common use of tritone substitution occurs on the V chord in ii-V-I progression. However, you can apply it in any situation where a ii-V relationship is present in the chord progression. For example, a iii-vi-ii-V progression has two ii-V relationships in it.
- iii-vi
- ii-V
In the iii-vi-ii-V chord progression above, you can replace the vi chord (A-7) and the V chord (G7) with tritone substitutions and still preserve the general harmonic movement of the progression while incorporating chromaticism.
Applying Tritone Substitutions in Your Jazz Solos
Let’s learn a line you can play over the iii-bIII7-ii-bII7 progression discussed above:
For more on tritone substitutions, check out this article on using tritone subs in your jazz solos.
Secondary Dominants
A secondary dominant chord temporarily tonicizes a non-tonic chord in a chord progression.
You have a secondary dominant chord when you take a target chord and precede it by a non-diatonic dominant chord a perfect fifth below or perfect fourth above that target chord.
Also known as borrowed dominants, secondary dominants are common chord substitutions in jazz music. Secondary dominant chords are often written into the chord progressions of jazz tunes.
For example, in a iii-vi-ii-V chord progression in C major (E-7-Am7-Dm7-G7), we can replace the iii, the vi, and the ii chords with their secondary dominant substitutions.
- The iii chord, or E-7, can be substituted with E7 (III7), the V7 of the vi chord.
- The vi chord, or A-7, can be substituted with A7 (VI7), the V7 of the ii chord.
- The ii chord, or D-7, can be substituted with D7 (II7), which is the V7 of the I chord.
The new chord progression is III7-VI7-II7-V7 or E7-A7-D7-G7.
Secondary Dominants in Chord Progression
You might recognize these changes as the iconic bridge to Rhythm Changes, which uses a III7-VI7-II7-V7 chord progression in Bb or D7-G7-C7-F7.
Diminished Substitutions For Dominant Chords
Dominant chords and diminished chords share some common tones that allow you to substitute dominant chords for diminished chords in chord progression.
Let’s compare an A7 chord to a Bb diminished chord and explore the common tones.
A7
- 7th: G (Abb)
- 5th: E (Fb)
- 3rd: C# (Db)
- Rt: A
B Flat Diminished
- 7th: Abb (G)
- 5th: Fb (E)
- 3rd: Db (C#)
- Rt: Bb
Note that diminished chords are unique in that each note in the chord is always a minor third away from the adjacent notes in the chord.
They are symmetrical, in other words. This means a Bb diminished chord is functionally the same as a C# diminished chord, which is functionally the same as E and a G diminished chords. That means you can replace A7 with any of those diminished chords; the result is the same.
You end up implying a rootless b9 dominant chord.
All four of these diminished chords are functionally equivalent to an A7b9 chord and can be used to substitute an A7 chord in any chord progression:
Diminished Substitute Chords in Chord Progressions
Let’s look at a common example of diminished substitute chords in action!
Let’s take a I-VI-ii-V chord progression in C. That’s Cmaj7, A7, D-7, and G7.
Instead of an A7 chord (VI chord), let’s use a C#dim chord (#i chord).
A7 Chord
- 7th: G
- 5th: E
- 3rd: C#
- Rt: A
C# Diminished Chord
- 7th: A# (Bb or b9)
- 5th: G
- 3rd: E
- Rt: C#
They are basically the same chord in terms of function, however the C#dim chord gives you chromatic movement in the root note as you move from the I to the #i to the ii.
Check out this article on how to substitute a dominant chord to learn more about this diminished chord substitution.
Modal Interchange
When you use modal interchange, you “borrow” a chord from another mode. Often, this mode is the parallel minor key. Many common chord substitutions are borrowed from the parallel minor. These substitutions are often written into jazz tunes.
Borrowed chords create harmonic interest by breaking out of the diatonic landscape while still being rooted to the tonic in some way.
Let’s compare the diatonic chords in C major and the chords from its parallel minor key, C minor.
Here are the diatonic chords in the key of C:
Here is the parallel minor key of C minor:
Both of these parallel keys are tied to the tonic of C, but they offer different tonalities. Borrowed harmony gives you more options when it comes to chord substitutions.
Let’s explore some of the common chord substitutions pulled from the parallel minor key.
Minor iv Chord
The minor iv chord substitution is perhaps the most common example of borrowed harmony. In the key of C major, the IV chord is major. However, in the parallel minor, it is minor. A great example of this chord substitution in action can be found in the jazz tune All of Me.
This progression also features a secondary dominant chord and a diminished chord substitution!
bVII Chord (Backdoor ii-V)
One common chord substitution is the “backdoor ii-V,” which replaces the V chord with the VII chord from the parallel minor key. In C minor, the VII chord is Bb7.
A Bb7 chord shares some common chord tones with G7b9/#9 chord:
G7b9/#9
- #9: Bb
- b9: Ab
- 7th: F
- 5th: D
- 3rd: B
- Rt: G
Bb7
- 7th: Ab
- 5th: F
- 3rd: D
- Rt: Bb
You can hear examples of this chord substitution in tunes like Stella By Starlight and Misty.
For more on modal interchange, check out this article on using borrowed chords. Check out this article if you want to know more about relative minor and parallel minor.
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