How Chord Progressions, Roman Numerals and Songwriting Intersect

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Songwriter and PenThrough the history of music, particularly in the so-called western world, not much has changed with regard to how chord progressions work. In most popular music genres, the kinds of progressions used are very similar to, or at least related to, the progressions used by composers for the past several centuries. In most music theory courses, chords are referred to by using Roman numerals. This way of identifying and describing chords can work quite well in the popular music world as well. Let’s take a look at how Roman numerals (which I’ll refer to as R.N.) work, and how they can be useful to songwriters.

We know that there are seven chords that naturally occur in any major key. For example, the key of C major produces the chords C, Dm, Em, F, G, Am, and  Bdim.

As you can see, some of the chords are major (C, F, and G), some are minor (Dm, Em and Am), and one is diminished (Bdim). When we describe these various chords by using R.N., the common method is to use upper case R.N. for the major ones, and lower case for the minor and diminished. (Augmented chords, which occur by altering a tone in major keys, are also labeled with upper case numerals.)

It’s easy enough to apply R.N. to these various chords. Since C is the first note (also called the tonic note) of C major, a chord based on the note C gets an R.N. of I. A chord based on D in this key will produce a minor chord, so it gets an R.N. of ii (lower case, because it’s minor).

So you can represent those seven chords (C Dm Em F G Am Bdim) with these seven R.N’s: I ii iii IV V vi vii. (The vii-chord often shows a small ‘o’ to the upper right of the vii, to indicate that it is diminished.)

So what’s the use of that? It seems like you’re simply taking one naming system (C, D, E, etc), and replacing it with another (I, ii, iii, etc).

R.Ns do more than simply tell us which chords are which. They help us accomplish two things:

  1. They can help us transpose music to other keys, or to see relationships within chord progressions.
  2. They help us identify the functions of the different chords within a song.
Let’s look at each of those points separately. In the case of transposing music, R.Ns identify the root of the chord within the key, so moving it to a new key is very simple. If a progression is: C  Dm  G  Am, the Roman numerals will be I  ii  V  vi. To transpose, you simply build new chords by finding the chord roots represented by the R.N. in a new key. So if you’re transposing to E major, instead of transposing everything up a major 3rd, you simply build chords on the 1st, 2nd, 5th and 6th notes of the new key of E major, giving us: E  F#m  B  C#m.

Secondly, and arguably more importantly, R.Ns allow us to quickly identify the various functions of the chords. They tell us which chord is the tonic (representing the key), which one is the dominant, and so on. This can be important as you compare one chord progression to another. Roman numerals allow you to instantly compare one song’s progression to a different song in a different key. By using R.N., you can tell that C  Dm  G  Am is, on a theoretical level, identical to E  F#m  B  C#m.

It’s a worthwhile exercise to convert pop song progressions to Roman numerals, because it allows you to do a level of musical analysis that’s difficult to do in any other way.

Here is “Hey Jude” (McCartney & Lennon) in R.N.: I  V  V7  I  IV  I  V  I.

Why not take one of your own favourites and try your hand at converting it.

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Written by Gary Ewer, from “The Essential Secrets of Songwriting” website.
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5 Comments

  1. Hi Gary,
    I’m pretty new at dabbling with songwriting and I have purchased your set of ebooks. One area where I am really having difficulty is in understanding the concept of a turnaround. I originally came across this in Rikky Rooksby’s book on ‘A Songwriting Sourcebook’. I didn’t quite get the point there but I discovered that you had made a post (which I have read.) But that didn’t get me much further.
    What I need to look at is a couple of examples of the turnaround in the context of a larger segment of a song. Perhaps if you could give me a link to some that would be really fantastic.

    Thanks

  2. I write chord and lyrics sheet for my guitarist using Roman Numerals, and he always asks for me to write it in the key we’re playing! I keep telling him to practice reading Roman Numerals, since the vocalist might one day ask to sing in a different key, but I don’t think he’s practicing.

    Cheers,

  3. Awesome article, as usual, Gary!
    I learned early on to always think in roman numerals when I am writing chord progressions.

  4. Hey Gary,

    Great article. But I have a question…In the paragraph which begins with “Secondly, and arguably more importantly…you can tell that C Dm, G, Am is, on a theorectical level, identical to E A B C#m”. But didn’t you mean to say “C Dm G Am is identical to E F#m B C#m? If we are in E major, then F#m would be the ii (minor chord). Unless I missed something :-).

    Roger R.
    Freeport, NY

    • Hi Roger- Thanks for catching that error. I’ve corrected it now. (I was going to say that I purposely put the error in, to see if anyone would catch it, but… I think you’d see through that. 😉

      Thanks again,
      -Gary

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