Changing Chords to Extend a Musical Line

Simple chord substitutions can do more for your music than simply vary the sound.


“The Essential Secrets of Songwriting” eBook Bundle“The Essential Secrets of Songwriting” 6-eBook Bundle (plus a FREE copy of “From Amateur to Ace: Writing Songs Like a Pro”) is written by Gary Ewer, designed to straighten out your technique and get you writing better songs.

spaceRead More about the Songwriting Ebooks


Singer guitarist songwriterMost of the chords you’ll ever choose for your songs will be so-called diatonic chords. A simple definition of “diatonic” is any chord that naturally belongs to the key you’ve chosen.

If your song is in C major, most of your chords will be chosen from the following list of seven:

C (I) | Dm (ii) | Em (iii) | F (IV) | G (V) | Am (vi) | Bdim (viio)

You can group those chords together into three categories:

  1. The tonic chord (I), plus others that could act as a nice replacement for the tonic: iii, vi.
  2. The subdominant chord (IV), plus others that could act as a nice replacement for the subdominant: ii.
  3. The dominant chord (V), plus others that could act as a nice replacement for the dominant: iii, viio.

And in fact, there is considerable crossover when you think about which chords could replace other ones. For example, the IV-chord (F) could be used in place of a tonic chord, as long as the right notes are being used in the melody. But that list above gives us the general idea.

So why would you ever consider substituting chords? Getting a better variety of sounds is the main reason. Let’s take a standard progression like: C F G C (I IV V I). You could change the second chord, F, to a Dm — as long as your melody note will accommodate that change.

It’s an interesting musical exercise to take standard progressions you might have used in your latest song, and experiment with some chord substitutions:


Possible alternatives:

  • C  F  Dm  G  (C…)
  • C  Am  F  Em  (C…)
  • C  Am  F  Bdim/D  (C…)
  • C  F  Dm  G  (Am…)

It’s that last one, C  F  Dm  G  Am, that I want to take a closer look at. You’ll notice that the final chord, which was a C, has been changed to Am. Other than providing a nice variety of sound, it happens to occur right at the end of the progression. And that has a particular benefit: it allows you to extend the musical line, and give you another chance to “go around again.”

Here’s what I mean. The progression C  F  Dm  G  C starts very strongly in C major, and then is followed by chords that emphasize that key, then ends on the tonic. By choosing to avoid ending on the C again, but rather end on a substitute, Am, you remove the sense of finality that comes from the original progression. With Am, the progression sounds like it needs something more in order to end in C major. And that’s often a good thing.

Let’s say that your song’s chorus features a progression of C  F  Dm  G  C, played four times. Each time you return to the C, a bit of musical momentum is compromised. Now, let’s say that you decide to replace the 2nd and 4th run-through of that progression with Am, with the Am becoming the first chord of the next phrase. You now get this:

//// //// //// //// |//// //// //// //// | repeat...
C    F   Dm   G      Am   F    Dm   G    | repeat...

By starting every second phrase on the Am chord, you give the listener the sense that more is coming, and it doesn’t allow the musical momentum to die away as would possibly happen with the constant return to the tonic.

So look for opportunities to change tonic chords to vi-chords (i.e., changing C chords to Am) once in a while. You help boost and maintain listener interest, and it works particularly well in progressions that are very repetitive.


Gary Ewer

Written by Gary Ewer. Follow on Twitter“The Essential Secrets of Songwriting” 6-eBook Bundle looks at songwriting from every angle, and has been used by thousands of songwriters. How to use chords, write melodies, and craft winning lyrics.  (And you’ll receive a FREE copy of “From Amateur to Ace: Writing Songs Like a Pro.“)

Posted in Chord Progressions and tagged , , , , , , .

One Comment

  1. Substitution By Function, that first came to my notice when I was trying to analyse The Beatles songs back in the sixties John and Paul were prolific at this technique

    Its a good idea for writers to understand the function of chords TONIC – SUB DOMINANT
    and DOMINANT of course this only applies to someone who can play a keyboard or a guitar Another excellent post Gary Thank you once again

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.