Functional Harmony Tonic, Dominant, and Subdominant Functions Explained

Functional Harmony: Tonic, Dominant, and Subdominant Functions

Functional harmony is the system that explains why chord progressions feel logical, emotional, and satisfying instead of random. Rather than seeing chords as isolated shapes, this approach assigns each chord a role inside a key.

These roles create:

Tension
Movement
Resolution
Direction

In this guide, we’ll explore the three main harmonic functions:

Tonic
Subdominant
Dominant

We’ll also cover substitutions, secondary dominants, and passing chords, with practical examples for composers, guitarists, and producers.

1. The Three Main Harmonic Functions

Every tonal song is built around a balance of these three forces. Think of them as musical gravity.

Function	Purpose	Emotional Role
Tonic	Stability	Rest, home, resolution
Subdominant	Preparation	Movement, transition
Dominant	Tension	Expectation, climax

Almost every popular progression is just a creative way of moving between these.

2. Tonic Function: The Musical “Home”

The tonic represents stability and rest. It is where progressions feel complete.

Scale Degrees

Key Type	Primary Tonic
Major	I
Minor	i / vi

Example (C Major)

C (C - E - G)
Am (A - C - E) (relative minor tonic)

Characteristics

Feels resolved
No strong urge to move
Sounds “finished”

Common Tonic Chords

Degree	Chord Type
I	Major / Maj7
vi	Minor / m7
iii	Minor / m7

Usage

Beginning of songs
End of phrases
Chorus resolution
Final cadence

Song Examples

Let It Be – The Beatles
Someone Like You – Adele
No Woman No Cry – Bob Marley

3. Dominant Function: Creating Tension

The dominant is responsible for tension. It wants to resolve. It needs to resolve. Ignoring it feels wrong.

Scale Degree

Degree	Function
V	Dominant

Example (C Major)

G (G - B - D)
G7 (G - B - D - F)

The tritone inside G7 (B–F) creates instability that pulls toward C.

Characteristics

Strong tension
Forward motion
Resolution pressure

Common Dominant Chords

Degree	Chord Type
V	7, 9, 13
vii°	dim / half-dim

Usage

Cadences
Build-ups
Climaxes
Pre-chorus sections

Song Examples

Hey Jude – The Beatles
Every Breath You Take – The Police
Hotel California – Eagles

4. Subdominant Function: Preparing the Tension

The subdominant sits between stability and tension. It prepares the dominant.

Scale Degrees

Degree	Function
IV	Subdominant
ii	Subdominant

Example (C Major)

F (F - A - C)
Dm (D - F - A)

Characteristics

Movement
Expansion
Mild tension
No strong resolution

Common Subdominant Chords

Degree	Chord Type
IV	Major / Maj7
ii	Minor / m7
vi	Sometimes

Usage

Verse development
Transition sections
Pre-dominant areas

Song Examples

Brown Eyed Girl – Van Morrison
With or Without You – U2
Stand By Me – Ben E. King

5. Basic Functional Progressions

Here are classic functional templates used everywhere:

Major Key

I – IV – V – I C – F – G – C

I – ii – V – I C – Dm – G – C

vi – IV – I – V Am – F – C – G

Minor Key

i – iv – V – i Am – Dm – E – Am

i – VI – III – VII Am – F – C – G

You’ve heard these thousands of times. That’s not an exaggeration.

6. Harmonic Substitutions

Substitutions replace a chord with another that has the same function. The structure stays. The color changes.

6.1 Relative Substitution

Major and minor relatives share notes.

Original	Substitute
C	Am
G	Em
F	Dm

Example

C – F – G Am – F – G

Effect

Softer sound
More emotional
Less predictable

6.2 Tritone Substitution (Jazz)

A dominant can be replaced by another dominant a tritone away.

Original	Substitute
G7	Db7

Example

C – F – G7 – C C – F – Db7 – C

Effect

Chromatic bass
Jazzy color
Smooth voice leading

6.3 Secondary Dominants

Dominants that target chords other than I.

Function	Example
V/V	D7 → G
V/ii	A7 → Dm

Example

C – D7 – G – C

Effect

Temporary tension
Forward momentum
More harmonic depth

7. Passing Chords

Passing chords connect main chords smoothly.

7.1 Chromatic Passing Chords

Move by semitone.

C – C#dim – Dm – G7

Creates smooth bass movement.

7.2 Diatonic Passing Chords

Stay in key.

C – Dm – Em – F – G

Natural and melodic.

7.3 Approach Chords

Target the next chord.

Am – Ab – G

Creates anticipation.

8. Functional Harmony in Different Genres

Classical

Clear cadences
Strong tonic-dominant pull
Structured forms

Jazz

Heavy use of ii–V–I
Tritone subs
Extended dominants

Pop / Rock

Simplified functions
Loop-based progressions
Modal influence

Metal / Progressive

Function mixed with modal harmony
Delayed resolution
Extended tension

9. Practice Exercises

1. Functional Analysis

Take any song and label:

I – vi – IV – V T – T – SD – D

Do this daily. Your ear will evolve.

2. Substitution Practice

Rewrite:

C – F – G – C

As:

Am – Dm – Db7 – C

3. Composition Drill

Write 8-bar progressions using:

2 tonic chords
2 subdominants
2 dominants
2 substitutions

Force balance.

4. Guitar Application

Practice each function in all positions:

Tonic shapes
Dominant voicings
Subdominant inversions

This builds fretboard logic.

10. Common Mistakes

❌ Overusing Tonic

Too much I = boring.

❌ Avoiding Dominant

No tension = no story.

❌ Random Substitutions

If it breaks function, it breaks flow.

❌ Ignoring Voice Leading

Good harmony moves smoothly.

Conclusion

Functional harmony is the hidden system behind most Western music. When you understand how tonic, subdominant, and dominant interact, you stop guessing and start composing with intention.

Mastering this gives you:

Better progressions
Stronger melodies
More emotional control
Faster composition

It’s not about memorizing chords.
It’s about understanding musical gravity.

Learn the forces.
Then bend them.