Functional harmony is the backbone of most of the music you listen to daily. In other words, it’s everywhere! In fact, it’s so ubiquitous that you might not give it much thought.
However, having a solid understanding of functional harmony—including how and why it works—is crucial for any jazz musician to truly master music theory! That’s why we’re going to spend some time outlining everything you need to know about functional harmony.
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What Is Functional Harmony in Music Theory?
Let’s cut to the chase and establish a definition. What is functional harmony?
Functional harmony is the system of organizing chords so that each one serves a specific role within a key. Instead of seeing chords as isolated musical objects, functional harmony connects chords through their relationship to a tonal center, or what we call a key.
That’s why to understand how functional harmony works, you need to understand the scale degrees of major and minor scales and be able to apply Roman numeral analysis to the different chords you can build from these scales.
We won’t spend too much time talking about these aspects of music theory. However, check out these resources if you want to understand scale degrees and Roman numeral analysis better:
In summary, chords aren’t random when you are working with functional harmony. Each chord in a chord progression comes from a diatonic scale and has a specific purpose that propels the progression forward.
Musicians group diatonic chords—chords built from these diatonic scales—into three categories that we’ll introduce now. Check out this article for more on diatonic scales.
Three Types of Chord Function in Functional Harmony
Functional harmony divides the seven diatonic chords into three groups, regardless of whether you are playing in a major or minor key:
- Tonic Function (three chords)
- Predominant Function (two chords)
- Dominant Function (two chords)
1. Tonic Function
Tonic function chords are built on the 1st, 3rd, and 6th scale degrees (I, iii, and vi chords). These chords sound stable and at rest. You probably could have guessed that the I chord was a tonic function chord, but you may not have imagined the iii or vi chords having tonic function too.
However, the vi chord in major keys is the I chord (or tonic chord) in minor keys, and the III chord is basically an extension of the I chord. A C major chord is C-E-G, and an E minor chord is E-G-B.
2. Predominant Function
Predominant chords are built on 2nd and 4th scale degrees (ii and IV chords). They are like setup chords that prepare us for the dominant chord. Think about the ii-V-I progression. Here, we start on the ii chord or predominant chord before moving to the dominant chord.
3. Dominant Function
Dominant function chords built on 5th and 7th scale degrees (the V and vii° chords). These chords contain the leading tone (the 7th scale degree), which naturally resolves upward to the tonic. In the key of C, that would be the B to C resolution.
Every chord progression in tonal music can be understood through this framework. Whether it’s a Bach chorale, a jazz ii–V–I, or a pop song’s I–V–vi–IV, functional harmony explains why the chords feel like they “make sense.”
How Functional Harmony Works
Most chord progressions follow a logical flow from tonic chords to predominant chords, to dominant chords, and then back to tonic chords. This is a simplification, and you can find many chord progressions that deviate from this straightforward pattern.
This flow—tonic → predominant → dominant → tonic—creates the archetypal harmonic progression. It’s why a ii–V–I in jazz works so powerfully, and why a I–IV–V–I in classical or rock music feels conclusive. You can use this formula when creating chord progressions of your own.
Functional harmony helps you understand why chords move the way they do, and how to use that knowledge in composition, improvisation, and analysis. And remember—we can always break or at least tweak the rules.
Check out this article for more on jazz chord progressions.
Now that we’ve outlined how functional harmony moves through tonic, predominant, and dominant roles, let’s see how these functions appear in actual major and minor keys.
Functional Harmony in the Major Scale
Let’s start with the diatonic chords in major keys. Take C major as an example:
- I – C major (tonic)
- ii – D minor (predominant)
- iii – E minor (tonic support)
- IV – F major (predominant)
- V – G major or G7 (dominant)
- vi – A minor (tonic support)
- vii° – B diminished (dominant)
Tonic Function in Major Keys
Let’s break down the tonic function chords in greater detail.
- I: The main tonic chord is considered the home base of the key.
- iii: Shares two notes with I (C–E–G vs. E–G–B), so it functions like a weaker tonic.
- vi: The “relative minor.” It often substitutes for tonic or moves toward predominant chords. It also shares two notes with the I chord (C-E-G vs. A-C-E).
Predominant Function in Major Keys
Let’s break down predominant chords in greater detail:
- ii: The classic setup for V. In jazz, ii–V–I is the bread-and-butter progression. Check out this article to learn more about the ii-V-I progression.
- IV: A strong predominant, often moving to V (think I–IV–V–I).
Dominant Function in Major Keys
Let’s break down dominant function chords in greater detail:
- V (or V7): The central dominant chord. Its leading tone (B in C major) resolves to tonic.
- vii°: Fully diminished triad or half-diminished seventh chord. It’s a substitute for V and resolves directly to I.
This structure explains why the most common types of chord progressions in tonal music feel inevitable: they’re simply moving through tonic → predominant → dominant → tonic.
BEFORE YOU CONTINUE...
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Functional Harmony in the Minor Scale
Minor keys are a bit more complex because composers usually draw from three different minor scales to make up for a weak dominant chord in the natural minor scale.
Here are the three minor scales composers pull from when creating chord progressions in minor keys.
- Natural Minor Scale
- Harmonic Minor Scale
- Melodic Minor Scale
Natural minor
- A-B-C-D-E-F-G-A
Notice the whole step between the seventh and first scale degrees. The lack of a leading tone, or a half step between the seventh and first scale degrees, creates a weak v chord that lacks that strong resolution back to the tonic chord. It’s why we need other minor scales.
Harmonic minor:
- A-B-C-D-E-F-G♯-A
The G# makes the V chord a major chord, giving us a proper dominant chord.
Melodic minor (ascending):
- A-B-C-D-E-F♯-G♯-A
Like with harmonic minor, the G# makes the V chord a major chord, giving us a proper dominant chord.
Check out this article to learn more about the three minor scales.
Diatonic Chords in A Natural Minor
- i – A minor (tonic chord)
- ii° – B diminished (predominant)
- III – C major (tonic support)
- iv – D minor (predominant)
- v – E minor (dominant)
- VI – F major (tonic support)
- VII – G major (dominant function)
Here are the chords you can build from the natural minor scale. Notice that the v chord (E minor) doesn’t have a strong dominant function because it lacks the leading tone (G♯) that pulls back to the tonic by a half step.
That’s why we need to use certain chords from other minor scales—harmonic minor and melodic minor. They both contain raised 7th scale degrees, creating a proper dominant chord—E major as opposed to E minor.
Functional Roles in Minor Keys
The functional roles of the chords are the same as in major keys. It’s only the quality of the chords that changes. Check out this article for more on chord qualities.
Tonic Function in Minor Keys
- i: This is the main tonic chord in minor keys and serves as the home base.
- III: This is the relative major chord and contains many of the same notes as the i chord. A minor is A-C-E, and C major is C-E-G.
- If you borrow from the melodic or harmonic minor scale, you can also use the III#5 chord, which has a G# instead of G. Normally, the G# would be a non-chord tone, but using the G# gives us a leading tone and a stronger pull back to the i chord.
- VI: This is a tonic support chord and can substitute for the tonic chord occasionally. It shares many of the same notes as the i chord. A minor is A-C-E, and F major is F-A-C.
- If you borrow from melodic minor, which has an F#, you get a vi° chord instead. This is a totally valid chord substitution that you can borrow and use in your minor chord progressions.
Predominant Function in Minor Keys
- ii°: Like major keys, the ii° chord is a predominant chord that sets up the dominant. When borrowing from melodic minor, the chord quality changes. Instead of a B diminished triad, B-D-F, you get a B minor triad, B-D-F#, because the scale has a raised 6th degree.
- iv: The iv chord is also a predominant minor chord that becomes major if you use melodic minor. The F# in melodic minor turns this D minor triad (D-F-A) into a D major triad (D-F#-A).
Dominant Function in Minor Keys
- v: When using the natural minor scale, the v chord is a weak dominant function chord because of the G natural. Often, this chord is replaced by a major-quality chord, transforming the G in the E minor chord (E-G-B) into a G#, thereby changing the chord’s quality to major (E-G#-B).
- You’ll often see the dominant chord peppered with non-chord tones that add extra tension and color to the harmony.
- VII: When using the natural minor scale, the VII chord is a major chord built on the subtonic scale degree (minor seventh).
- However, when using the harmonic or melodic minor scale, this chord becomes a diminished chord. G-B-D, or a G major chord, becomes G#-B-D, or a G# diminished chord.
Check out these articles to learn more about chord extensions, chord substitutions, and secondary dominants.
Incorporating Functional Harmony and Music Theory into Your Jazz Practice
Functional harmony is essential for both analysis and composition. Understanding functional harmony helps you as a composer, improviser, and listener. You begin to hear why progressions resolve the way they do and how you can manipulate them for emotional effect.
Hearing and Practicing Functional Harmony
Theory means little until you can hear it and apply it. Here are some ideas for practical exercises you can employ in your jazz practice.
Ear Training
- Practice recognizing tonic, predominant, and dominant functions by ear.
- Sing scale degrees: 1–3–5–7 (tonic), 2–4–6 (predominant), 7 leading to 1 (dominant resolution).
- Play V7 → I cadences in every key and listen for the pull of the leading tone.
Check out this article on ear training exercises for more information.
Playing Exercises
- Take a progression like ii–V–I in C (Dm7 → G7 → Cmaj7). Transpose it to all 12 keys.
- Try in Eb major: Fm7 → Bb7 → Ebmaj7.
- Practice in minor: iiø7–V7–i. For example, Dm7♭5 → G7 → Cm.
The more you practice hearing and playing functional harmony, the more naturally it shows up in your improvisation and composition.
Why Functional Harmony Still Matters
Even in an age of modal harmony, free improvisation, and contemporary genres, functional harmony remains the bedrock of tonal music. It explains why chord progressions work, why melodies resolve the way they do, and how to create music that balances stability and tension.
It’s not just theory for its own sake. It’s a tool for making music. Understanding functional harmony prepares you to:
- Write chord progressions that feel satisfying.
- Analyze standards and classical works with clarity.
- Improvise solos that follow harmonic motion.
- Hear deeper into the music you play and listen to.
Functional harmony is the grammar of tonal music, and once you internalize it, you are one step closer to speaking the language fluently.
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