Chord and Harmonic Functions in Music (A Crash Course)

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  • What is the harmonic function of chords?
  • Learn about tonic, subdominant, and dominant.
  • Discover how to use harmonic functions for jamming, composing, and songwriting.

I’ll be the first to admit it. I spent many years “winging it”. I would play a chord and then stumble into the next chord by trial and error. I made it sound like a good thing by calling it “intuition” and wore it as some facetious self-taught badge of honor.

That’s all dandy, but I was the only one paying the price for it. I would get stuck, confused, and frustrated. It also made it impossible for me to grasp chromatic harmony. You gotta learn the rules to break ‘em, right?

Over time, I realized that chords are neither indiscriminate nor random. Chord progressions are formed on a solid foundation of diatonic harmony rather than intuition. Composers build chord progression for a piece of music with a solid understanding of these functions.

Good composers select and place chords with a specific intention. In turn, these chords create movement, restfulness, or instability to convey the creative aspirations of the musician.

I don’t mean to sound like that shady guy on late-night adverts, but learning about harmonic functions changed my life! Well, at least my musical life. In this article, we’ll look at harmonic functions and learn how you can use them to improve your improvisation and songwriting skills.

Harmonic Function: The Purpose of Chords

Every musical element has a “function” which describes the role of that element in the larger context of a piece of music. Chords are no exception. They have what we call “harmonic function” or “diatonic function” in tonal music.

I say diatonic because it only applies to tonal music – the stuff with a home key (which is a majority of the music). A home key has a tonic. The tonic refers to the primary note or first scale degree of any diatonic scale (C in C major).

A tonic triad is stable and the primary focus of the melody and harmony.

All the chords in the key have a purpose based on when/where/how you place them. If you do it intuitively, that purpose still exists but is totally haphazard. Understanding harmonic function will improve your listening, anticipation, and composition.

What Role Do Chords Play in Music Theory?

Harmonic function is the tendency of chords to rest or progress to other chords. It is understood through a categorization of diatonic chords into three functions or families – Tonic (T), Subdominant/Predominant (S), and Dominant (D).

If I strip it of all the music theory jargon, I would say chord function is an interplay of three “vibes” – unstable, tense, restful. Each vibe becomes a category or family of chords because of the way they make you (and your audience) feel.

Thus, it defines the “chord quality” in relation to a tonal center and helps you approach it as a dynamic force of creative expression and storytelling.

How Do You Harmonize A Scale With Chords?

Do you remember how to find out the chord harmony of any parent scale in a diatonic situation? Just stack diatonic thirds!

I will harmonize the C major scale but you can apply the same concept to other scales and even derive four-note chords (such as maj7 or m7). I’ll elaborate on that briefly.

Let’s write down the C major with roman numerals:

I ii iii IV V vi vii∘ I

We know that the first chord is a C major triad (C E G). To find the other chords, we will stack diatonic thirds i.e. the third of D in this scale is F, and the third of F is A so that gives us the Dm triad (D F A).

If you look at the table above, we are just picking alternating notes: C-E-G, D-F-A, E-G-B, and so on. Once we get the three notes (chord spelling), we can determine if the triad is major, minor, diminished, or augmented. Read up on our illustrated guide to the types of triads to learn more.

You can continue to use this process to find the triad for every scale degree and you will end up with Cmaj, Dm, Em, Fmaj, Gmaj, Am, and Bdim. Here, C is our diatonic tonal center and the others are the triads built on the remaining scale degrees.

It’s important to learn this concept rather than memorize a diatonic series of chords or numerals. It will enable you to harmonize any scale with triads of four-note chords. Plus, understanding how to harmonize a scale is the cornerstone of composition.

What Are The Three Musical Functions?

So far, we understand the music theory related to a key (tonal center) and how to form diatonic chords within a key. Now, we’ll see how these chords are categorized into three families based on chord functions and tendencies.

The 7 chords formed by harmonizing a scale can be ascribed to three-chord functions or families.

Tonic Family I, iii, vi
Dominant V, vii∘
Subdominant and Predominant IV, ii

Allow me to make a clear distinction. There is a difference between tonic and tonic function or dominant and dominant function, and so on.

The term dominant refers to the fifth scale degree of a diatonic scale. The term ‘dominant function’ refers to any chord that wants to ‘progress to the tonic’.

Yes, the dominant function includes the V (build on the 5th scale degree) but it also includes the vii∘ chord. The V7 is the dominant chord and the V and vii∘ serve the dominant function. It can be confusing because the chord functions derive their name from scale degree names.

Let’s learn more about each chord function and family:

Tonic Function (T) and Tonic Family

A chord that has a tonic function doesn’t create any emotion of wanting to go anywhere. It emanates the feeling of “home” – a term I use to describe the stability and tranquility of the chord. The function of tonic chords is also associated with a sense of completion or rest.

Scales are always named after the tonic and the triad on the primary note is always the most important chord for the key. This is the chord on which most songs begin or end (although this is not mandatory).

Every primary chord serves the tonic function. By primary chord, I am referring to the first chord built on the first scale degree. For example, C has a tonic function in the Key of C.

The vi (the relative minor) shares two notes with the I chord in a major scale, so it also serves the same harmonic function as the tonic. It’s frequently used as a substitute for the tonic chord. It is, however, a more melancholic version as opposed to the happy-sounding major tonic.

Dominant Function and Dominant Family (D)

The dominant function is in stark opposition to the tonic function. It is restless and unstable. Perhaps something you can liken to a homesick traveler. It wants to resolve and is associated with tension and “preparing for the tonic”, which will provide the resolution.

Dominant harmony has a dual function – to create tension and confirm the tonic.

In the key of C, the dominant chord or the G7 (built on the dominant scale degree) is the main member of the dominant family. You will witness the tonic-to-dominant-to-tonic (T – D – S) motion in countless songs across different genres.

The second chord in this family is the B half-diminished seventh. It’s the seventh degree, which has a strong pull to resolve to the tonic (up by half a step). It has a dominant function but it sounds more dissonant than the V7 chord, so it is not as common in pop music.

(Read more about dominant seventh chords here!)

Subdominant or Predominant Function (S or IV)

If tonic chords are stable and restful and the dominant function is unstable and tense, the subdominant function is a little bit of both – a middle ground. In some scenarios, it can be a less intense version of tension that dictates movement.

However, a chord with the subdominant function can travel to either of the other two functions i.e. it can migrate from the tonic and add to the buildup of tension or it can move to the tonic and “take you home”. In this way, it is rather flexible. The IV chord and ii chords have a predominant function.

However, many music scholars don’t subscribe to the idea of a ‘middling ground’. To them, harmonic functions are either weak or strong.

So, the subdominant is often called the “pre-dominant” and associated with the family of chords that are eager to move away from the tonic or towards the dominant family.

Chord Tendencies

Chords have a predisposition – a preference to progress naturally to certain chords. This is the chord’s tendency. Knowing it through the lens of harmonic functions can help you create meaningful progressions rather than constantly stumbling into what “sounds right”.

The tonic is open hunting season. The I chord can move to any other chord within the diatonic harmony. The other chord functions have a tendency to progress in a specific manner.

You can analyze your favorite songs using this knowledge. You will notice that chord progressions start stable (T), move through activity (S, D), and then end with stability (resolution).

For instance, any chord with a dominant function wants to progress to the tonic chord (V-I). The V (dominant) creates the tension and the I (tonic) creates the resolution. The ii chords have a predominant function – it prepares you for the dominant function. So, we can play ii-V-I.

Chord Prolongation and Functional Possibilities:

We can use other chords from the same family to ‘prolong’ the harmonic functions. So, you play an I – vi – V – I instead of an I – V – I.

Adding the vi will prolong the tonic function and reinforce the tonal center. You have managed to add a new chord to the progression without changing the harmonic focal point.

There are many possibilities of chord prolongation once you factor in chord inversions. For example, you can use the IV chord to prolong the tonic if you play it as a 6/4 (six-four chord).

That’ll lead us into static harmony, cadence, and a theoretical tizzy. So let’s stay on point and leave that for another day.

This table/chart will help you to understand the basics:


(C major)

Roman Numeral Scale Degree Chord Function Role of the Chord
C I Tonic Tonic (T) Tonic – Restful, stable
D ii Supertonic Subdominant (S) Predominant (precedes a dominant chord)
E iii Mediant Tonic (T) Tonic prolongation
F IV Subdominant Subdominant (S) Predominant
G V Dominant Dominant (D) Dominant – Unstable, tense
A vi Submediant Tonic (T) Tonic prolongation
B vii° Leading Tone Dominant (D) Dominant or tonic prolongation

Songwriting, Storytelling, and Harmonic Function

Better Composing and Songwriting Skills

Chord harmony can be equated to the personality of a song. If you know how chords function, you can use them to create and prolong moods consciously.

Do this to enhance the emotions you want to convey. Chords should always speak the same language as the lyrics.

Let’s say you want to end your song with a feeling of unrest. If this is the case, avoid chords with a tonic function or subdominant function. This narrows down your choices to the dominant family.

Let’s suppose you want to compose a stable-sounding verse for a song. You can dabble with the tonic family (tonic and relative minor). This can be an I-vi (C – Am) chord progression that can be heard in the peppy and ‘at-home’ Beatles tune Paperback Writer.

Beginners often try to include as many chords as they can, many of which are extensions or borrow from parallel keys. It sounds and looks smart, but does it serve the music? After all, the most popular songs don’t have complex or chromatic harmonies.

I, IV, V, and vi are the bread and butter of harmonic writing. So, it is to your advantage to start simple.

Improve Your Transcribing

Studying harmonic function can help you identify chords in a particular key behave. In turn, you can assign a function and sound (or emotion) to identify it easily by ear. This enables us to identify chords by ear, and quickly.

This is of immense value when you want to remember chord changes, anticipate chords, or play jazz standards in every key. Harmonic function is a great tool for memorizing tunes simply because you understand chord function at the fundamental level so it’s easy to remember what chords follow other chords.

The first step to all of this is to train your ear (relative pitch). You need to reach a point where you can listen to a chord (in the context of a key) and identify which of the three functions it serves (T, D, S).

It will make it easier to transcribe songs and improve your understanding of how composers use the tension-solution mechanism at large.

Understand (Diatonic) Chord Substitutions

Chord substitutions allude to how different diatonic chords within a chord family can be used interchangeably.

Now that you know the tonic, subdominant, and dominant families, you can exchange chords within each family because they have the same harmonic functions.

For example, the tonic chord family of a C major has C and Am7, and they can be substituted for one another. Or, in the same key, you can play a Dm7 instead of a Fmaj7. Listen to two progressions  in the audio below:

Progression 1: Cmaj7 – Am7 – G7 – Fmaj7

Progression 2: Em7 – Am7 – G7 – Dm7

In the second progression, I replaced the Cmaj7 with an Em7 (iii) as they both belong to the tonic chord family. Similarly, I replaced the subdominant chord – Fmaj7 (IV) – with the Dm7 (ii) as these belong to the subdominant family.

The overall feel of the chord progression doesn’t change. Yes, the progression sounds different, but there is no drastic change in the emotional impact on the listener. This is how harmonic function can be used to break the monotony without disturbing the underpinning emotion.

Improvisation and Jamming

It’s downright mandatory to know harmonic functions if you want to improvise effectively. It helps you spell out the harmony in your solos and anticipate where the chord will move to.

It’s extra helpful when you are jamming or ‘winging it’ as you stand in for another musician – there’s no chord chart to spell out the progression for you.

For example, you know the key and notice that the band is playing a chord with a dominant harmonic function (it sounds unstable). You can instantly tell that a G7 (V) or Bm7(b5) chord is being played. Based on the genre, you’ll narrow it down rather quickly.

It’s more likely to be a G7 in a country or pop song as opposed to a Bm7(5). Even if you play the Bm(75) instead of the dominant chord, you won’t sound bad because you are still within the same dominant function family of chords.

Wrapping Up

Chord functions are an important yet elusive part of music theory. At the surface level, harmonic function seems to be a simple theory. It’s one of those topics like syncopation where you can broadly explain it in a tweet or write a whole book about it.

Don’t fret if you find yourself confused after some study on this subject; we all are. This rabbit hole runs deep. Either way, it’s worth the investment because it opens doors to voice leading, intervals, tension-resolution, and other important harmonic concepts.

To further expand your knowledge of chords, harmony, and general music theory, here are some other articles to check out: