Chord Progressions

If a single chord is a data structure, a chord progression is an algorithm: an ordered sequence of chords that moves a listener somewhere over time. This chapter is about that ordering — why some sequences feel like "going home" and others feel like an endless forward loop — and how MidiSketch picks from 22 ready-made progressions.

Chord progression

A chord progression is an ordered sequence of chords played one after another, usually looping over a section of a song. Order matters: the same set of chords arranged differently produces a different emotional path. Progressions are written in degree (Roman numeral) notation so they transpose to any key — I-V-vi-IV means the same relationship whether you are in C, G, or any other key.

Harmonic function: home, away, and the pull back

Before looking at specific progressions, it helps to know that each chord in a key plays one of three structural roles. These roles are why progressions feel directional rather than random.

Tonic / subdominant / dominant function

Every chord in a key has a function — a structural job — and there are three of them. The tonic function (degree 1, I, and its stand-ins vi and iii) is home: stable, resolved, at rest. The dominant function (degree 5, V, and vii°) is maximum tension; it strongly pulls back toward the tonic. The subdominant function (degree 4, IV, and ii) is the in-between "away" zone that sets up the dominant. Most progressions are just a walk between these three poles.

Tension and resolution

Tension is the feeling that the music is unstable and wants to move; resolution is the release when it lands on a stable chord. Composers create tension (usually with a dominant chord) precisely so they can resolve it. The interplay of the two over time is the single most important engine of Western harmony — a progression is essentially a tension curve.

Tension curveA full phrase: I-IV-V7-I

The classic full sentence of tonal harmony: start at home (I), move away (IV), peak the tension (V7), and resolve (I). Almost any progression you analyze decomposes into some walk along this stable-tense-resolved cycle.

tensionresolutionStable, lifting, tense, resolved: progressions are tension curves over time.

The four-chord sentence above is the cleanest illustration of the cycle: it leaves home, builds, peaks, and returns. Almost every progression you analyze decomposes into some walk along this same stable-tense-resolved path.

Cadences: how a phrase signals "we arrived"

A progression needs punctuation. The musical equivalent of a period at the end of a sentence is the cadence.

Cadence

A cadence is a short chord motion that ends a phrase, most often the dominant resolving to the tonic (V→I). It is the harmonic punctuation mark that tells the ear a phrase has finished. The strength of the "arrival" depends on the chords involved — a V→I cadence is the strongest and most conclusive.

CadenceV to I: the strongest resolution

G7 contains the unstable pair B-F (a tritone), which "wants" to collapse onto C-E. That pull-and-release, called a cadence, is how phrases signal "we have arrived". Listen for the relief on the final C chord.

cadenceV-IThe dominant (V) pulls toward home (I) — release the tension and the phrase ends.

Notice that the resolution is driven by a single unstable interval inside the dominant chord that "wants" to collapse onto the tonic. That mechanism — and how to exploit it — is the subject of the next chapter on harmonic color.

The Royal Road: J-pop's signature loop

Not every progression resolves cleanly. Some are designed to keep floating forward, never quite settling, which is exactly what makes a chorus feel like it could loop forever.

Royal Road progression (王道進行)

The Royal Road progression (王道進行, ōdō shinkō) is IV-V-iii-vi, an extremely common loop in Japanese pop. Its defining trait is that it never lands on the tonic — it lifts on the subdominant, drives on the dominant, then sidesteps into minor chords instead of resolving home. The result is a bittersweet, perpetually forward-leaning feel.

Royal RoadThe "Royal Road" progression: IV-V-iii-vi

In C major this reads F → G → Em → Am. It never sits on the home chord, so it keeps floating forward — the reason countless J-pop choruses use it. MidiSketch ships it as one of the 22 preset progressions.

chordProgressionIdIV-V-iii-viThe signature J-pop loop: lift (IV), drive (V), shade (iii), land (vi).

Because it sidesteps the tonic, the Royal Road creates motion without closure — the harmonic equivalent of a loop that never returns to its initial state. MidiSketch ships this as one of its preset progressions, selectable by id.

The four-chord loop and the canon progression

The most recycled loop in Western pop is a close cousin: four diatonic chords that complete a full emotional arc and then repeat.

Four-chord loop / canon progression

A four-chord loop is any short four-chord cycle repeated throughout a song; I-V-vi-IV is by far the most recycled one. It is often confused with the canon progression (I-V-vi-iii-IV-I-IV-V), named after Pachelbel's Canon, whose first four chords walk the bass steadily downward. These loops are popular because four chords are enough to trace a complete home → away → sad → hopeful arc while staying simple enough to memorize instantly.

Four-chord popThe four-chord loop: I-V-vi-IV

C → G → Am → F. Hundreds of hit songs share this exact loop. It starts at home (I), wanders (V), darkens (vi), and brightens back (IV) — a complete emotional arc in four chords.

chordProgressionIdI-V-vi-IVHome, away, sad, hopeful — the most recycled loop in Western pop.

The I-V-vi-IV loop opens on I and, because it loops, lands back on it every four bars — unlike the Royal Road, which never touches the tonic at all. The arrival is the loop restarting rather than a cadence, which is why the progression feels resolved and still danceable on repeat. Both are just different orderings of mostly the same diatonic chords — the ordering is the whole design.

Borrowed chords: stepping briefly outside the key

Every progression so far stays inside the seven diatonic chords. A progression can also pull a single chord in from outside the key for a splash of color — without changing where the song calls home.

Borrowed chord (♭VII)

A borrowed chord is a chord taken from the parallel key (here, the parallel minor) and dropped into an otherwise diatonic progression. The most common one in pop and rock is ♭VII — in C major, a B♭ major chord. Its root sits a whole step below the tonic instead of the diatonic vii°, giving a bright, anthemic lift that falls back to I. It is the signature sound of the I-♭VII-IV-I rock cadence.

Borrowed ♭VIIThe ♭VII rock cadence: I - ♭VII - IV - I

C → B♭ → F → C trades the leading-tone pull of a diatonic cadence for a bright, plagal brightness. The ♭VII chord (B♭ major) is borrowed from the parallel minor; its root sits a whole step below the tonic instead of the diatonic vii°. This is the signature sound of countless rock and anime choruses. MidiSketch ships two such Rock presets, selectable via chordProgressionId like any other progression.

chordProgressionIdI-bVII-IV-IB♭ is borrowed from outside C major — a whole step below the tonic — for an anthemic, mixolydian lift.

I-♭VII-IV-I (C - B♭ - F - C) trades the leading-tone pull of a diatonic cadence for a plagal, mixolydian brightness — the move behind countless rock and anime choruses. MidiSketch ships two ♭VII progressions (the Rock presets), selectable like any other via chordProgressionId. They are not the only presets that step outside the key: AeolianPop is vi-♭VI-♭VII-I and NeapolitanPop is vi-iv-♭II-V-I, so ♭VI, ♭II and the minor iv appear too. The engine voices and analyzes all of them correctly.

Vamps: a progression can be tiny

Loop length is itself a stylistic choice. A progression does not need three or four chords; two are often enough to establish a mood.

Vamp

A vamp is a very short repeated progression — often just one or two chords — used as a hypnotic, atmospheric backdrop. Modern pop, lo-fi, and electronic styles lean on vamps because the relentless repetition is the point: it frees the melody and rhythm to carry the song. Short loops trade harmonic variety for groove and immediacy.

Two-chord vampProgressions can be tiny: Am-F loop

Not every song needs a long chord journey. A two-chord vamp (here Am ↔ F) creates a hypnotic, lo-fi atmosphere. Loop length is a stylistic choice: blueprints like BehavioralLoop intentionally exploit very short, repetitive loops.

loopvampTwo alternating chords already make a mood — modern pop loves short loops.

A two-chord vamp like Am↔F already carries a complete mood. MidiSketch treats loop length as a deliberate parameter: blueprints such as BehavioralLoop intentionally exploit very short, repetitive loops to maximize stickiness — a design we revisit in Chapter 7.

MidiSketch mapping

Concept	MidiSketch control	Notes
Choosing a progression	chordProgressionId (0-21)	22 preset progressions; getChords() lists them all
Borrowed chords	chordProgressionId	Rock presets I-♭VII-IV-I / I-IV-♭VII-I; also AeolianPop vi-♭VI-♭VII-I and NeapolitanPop vi-iv-♭II-V-I
How progressions are written	degree (Roman numeral) notation	e.g. IV-V-iii-vi, key-independent so it transposes to any key
Loop length as a style choice	short vamps vs. long cycles	BehavioralLoop blueprint exploits very short loops (forward reference, Chapter 7)

Engine reference: Harmony

Next chapter: Harmony & Color