Common Chord Progressions: Loops, Numerals and Why They Work
The chord loops that songwriters reuse most, in Roman numerals and in the keys of C and G, with the reasons they work and how to vary them.
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A common chord progression is a short loop of chords, usually four, that repeats under a melody. Many of the most reused loops share three features. Their roots move by fourths and fifths at least some of the time, neighbouring chords share notes, and the loop ends in a way that pulls back toward its start. The loops below are written in Roman numerals so that they transpose, with the chords spelled in C and G.
The loops you will hear first
The table lists the loops by name, their numerals, and the chords in the keys of C major and G major. The feel column describes the sound in general terms.
| Loop | Numerals | In C | In G | Feel |
|---|---|---|---|---|
| I–V–vi–IV | I V vi IV | C G Am F | G D Em C | open, widely reused |
| vi–IV–I–V | vi IV I V | Am F C G | Em C G D | the same chords, starting on minor |
| I–vi–IV–V | I vi IV V | C Am F G | G Em C D | often called the 50s progression |
| I–IV–V | I IV V | C F G | G C D | plain and direct |
| ii–V–I | ii V I | Dm G C | Am D G | a clear arrival |
| I–IV–vi–V | I IV vi V | C F Am G | G C Em D | a step down through the minor vi |
| Descending loop | I V vi iii IV I IV V | C G Am Em F C F G | G D Em Bm C G C D | a long, falling bass line |
The last row is the descending loop, often called Pachelbel-style. It is eight chords long, and it is named for the canon that is usually analysed with this sequence of roots. In D, that sequence is D, A, B, F sharp, G, D, G, A. The name refers to a style of descent over this root sequence, not to a single fixed bass line.
The first loop is a useful starting point, because each of its chords is in root position and its voicings are easy to reach. In C it is C, G, A minor, F.
The ii–V–I loop is a different kind of object. It is a cadence rather than a loop of four equal chords, and it ends on a tonic that sounds like rest. Repeated as a loop it sounds like a string of cadences, which is why it is more often the end of a phrase than the whole of one. The ii–V–I article covers its function in detail. In C it is Dm, G, C:
Why these loops work
Three properties recur. The first is shared notes. C major and A minor share two of their three notes, C and E, so the change from I to vi keeps most of the sound. A minor and F major share A and C. C major and F major share only C. The changes that keep more notes in common feel smoother, and most of the loops above use those changes.
The second is root motion. The roots in I–V–vi–IV are C, G, A and F. The motion from C to G is up a fifth, and from F back to C is down a fifth, which is the same as up a fourth. Strong root motion by fifths and fourths, which the circle of fifths makes visible, gives a loop a sense of direction, while the single step from G to A and the falling third from A to F keep the loop from sounding mechanical.
The third is the loop point, which is the chord that leads back to the start. The last chord of the loop decides how it closes. In I–vi–IV–V the loop ends on V, which returns to I, so the ear hears a dominant resolving to a tonic. That makes it a strong close, and the loop sounds complete each time around. In I–V–vi–IV the loop ends on IV and returns to I. That is a plagal motion, which confirms the key but closes more softly. In vi–IV–I–V the loop ends on V and returns to vi, a deceptive motion, so the loop does not sound finished and is easy to keep going. Played as a block, the same chords starting on the minor show that effect:
Varying a loop without changing it
A loop can be changed in a few ways that keep its numerals. An inversion changes the bass without changing the chord. In C, the sequence C, G over B, A minor, F moves the bass C, B, A, and only then F. The bass now steps down, which is a common way to add motion to a loop without adding a new chord.
A surprise chord changes one chord and keeps the rest. Replacing F major with F minor, which borrows the minor fourth from the parallel minor key (see the borrowed chords article), gives the loop a darker turn at its last chord. The notes are F, A flat and C, and the A flat is the only one that is not in C major.
A suspension is a quieter variation. Replace the G with Gsus4, which swaps the third, B, for the fourth, C, and then resolve it back to G. The sus chord is a colour, not a new harmony. It fits the dominant well, because the fourth falls to the third when the chord resolves.
The cheapest variation is rhythmic. Keep the four chords and move the changes: a chord that starts on the offbeat instead of the downbeat changes how the loop feels without changing a single note.
Transposing with numerals
Numerals describe the relation between chords, not the chords themselves, as the roman numeral analysis article explains. I–V–vi–IV in D is D, A, B minor, G. In F it is F, C, D minor, B flat. The shape is the same in all three keys, which is why songwriters write the progression once in numerals and then choose a key for the singer. The I–IV–V–I loop in C is C, F, G, C, and it is the same shape in every key:
Choosing the key is a separate decision from choosing the loop, and for most singers it decides where the melody sits.
Minor loops
Minor loops use the same numerals with lowercase letters for minor chords. Three are common. The first is i, VI, III, VII, which in A minor is A minor, F, C, G. Those are the same chords as vi, IV, I, V in C major, and the difference is the tonic, which the melody and the bass establish.
The second is the Andalusian cadence, i, VII, VI, V, which in A minor is A minor, G, F, E. The final chord is E major, not E minor, because the harmonic minor raises the seventh and the dominant needs its leading tone, G sharp. The third is i, iv, v, which in A minor is Am, Dm, Em, with the minor v.
Where loops mislead people
A loop is a skeleton. Writing a song with I–V–vi–IV and nothing else gives the chords and not the song, and the same loop can be heard in very different songs because the rhythm, melody and voicing are different. Treat the progression as the starting point and decide the other elements separately.
Numerals can also hide the function of a chord. The vi in C major is a relative minor, and in a loop it often sounds like a stable chord that shares notes with I. In a different key, or inside a song that stays on the minor, the same numeral may play a different role, so check the key before you assume the function.
Finally, a loop repeated without change becomes predictable within a few bars. The listener hears the pattern, and the chords stop giving information. Vary the rhythm, the voicing or one chord on each repetition.
What to do with it
Choose one loop from the table and play it in C, then in G, then in A minor. Sing a four-bar melody over the loop, and then change only the last chord to see how the ending changes. If the melody sounds finished over I, and unfinished over V, you have heard the loop point at work. Then write a verse on vi, IV, I, V and a chorus on I, V, vi, IV, and compare them, which is the subject of the song-form article.
Questions
What is the most common chord progression in pop music?
No single progression is the most common, and the claim is hard to check. The loops most often reused are I V vi IV, vi IV I V and I vi IV V, which is sometimes called the 50s progression. Each of them uses the same three or four chords in a different order.
How do you transpose a chord progression to another key?
Keep the Roman numerals and apply them to the new tonic. In C, I V vi IV is C G Am F; in D it is D A Bm G. The numerals describe the relationship between the chords, so the progression keeps its shape in any key.
Why does a chord progression feel like it wants to go somewhere?
Its last chord decides the pull. When a loop ends on V and returns to I, the ear hears a dominant resolving to the tonic, which is a strong close. When it ends on IV and returns to I, the motion is plagal and softer.
Can a common progression sound original?
Yes, because the sound depends on rhythm, voicing, register and the melody as well as the chords. Changing one chord, such as a borrowed minor fourth, or moving the progression to a different register changes the effect without changing the loop.
