Chord progression generator

What it's for

To find inspiration when composing: it generates proven chord loops (like I-V-vi-IV, the most famous in pop) in the key you choose.

How to use it

Play the chords in the shown order, looping them. The numbers below are the scale degrees: you can transpose them to any key.

Why progressions are written in roman numerals

A progression written as C-G-Am-F only works in C major. Written as I-V-vi-IV it works in every key, because the numbers give the degree of the scale and not the note: change key and the four chords move together. It is how musicians talk to each other when a piece has to be fitted to a singer's range.

The convention is that uppercase numerals are major chords and lowercase ones minor. It is not decoration: in a major key the degrees I, IV and V are born major and ii, iii and vi minor, and the seventh degree is diminished. That alternation is already written into the scale, and is not a choice.

The four chords that hold up half of pop

The I-V-vi-IV progression is probably the most used sequence in popular music of the last fifty years, and its strength lies in a balance: it starts stable, moves into tension, touches the minor colour and comes home through the softest degree. Its rotations — vi-IV-I-V, IV-I-V-vi — are the same circle read from another point, which is why they all sound alike.

The other two great classics are the twelve-bar blues, which alternates I, IV and V with an almost geometric symmetry, and the ii-V-I, the basic cell of jazz: two anticlockwise steps on the circle of fifths, that is the strongest movement in Western harmony.

What makes a progression convincing

Three things, and none of them is originality. The movement of the bass: if it falls or rises by nearby steps instead of leaps, the progression sounds smooth, which is why inversions written with a slash (C/E, G/B) appear everywhere. Held notes: if two neighbouring chords share a note, leaving it still makes the change feel soft.

And function: in harmony chords fall into three families, those that stay home (I, vi), those that move away (ii, IV) and those that pull back (V, vii). A progression that travels the three families in that order almost always works; one that jumps from home to tension and back sounds broken.

The progression is not the song

With the same four chords you can write a dance track, a ballad and a punk song: what changes is everything else, that is the rhythm they are played with, the tempo, the register of the instruments and above all the melody. A progression is a floor, not a building.

One practical point is worth remembering too: chord progressions are not protected by copyright, because they are common material. What is protected is the melody, that is the part you hum. It is why thousands of songs share the same progression without anyone having copied anyone.

Nearby tools

The notes of each chord are in Chord notes, the fingerings in Guitar chords. The map of keys is Circle of fifths, to change key there is Transpose chords and to play along Metronome.