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Chord Theory Can Be Complicated, But These Two Things Top the List

There’s a lot you can study about chords — about the way they work, how to choose them, and how one progression relates to another. All of it comes under the large umbrella called chord theory, and it’s a very large umbrella.

Some songwriters have a knack for it; it’s not something they have to consciously think about. They just have a feel for chords, and they are pretty good at coming up with interesting progressions.


How to Harmonize a MelodyWondering how chords support melodies, and how to add chords to your own tunes? Get “How to Harmonize a Melody.” It’s part of “The Essential Secrets of Songwriting 10-eBook Bundle.”


If chords have always been a bit of a mystery to you, you’re not alone. In some ways, chords work in our minds like language does. And some have a flair for language, and others have to work hard at it.

I can at least give you a bit of good news: while there’s a lot to know with regard to chords, there are two things that top the list for what you really need to know. And in fact, if you know these two things, you know enough to create some pretty good progressions:

  1. Most good progressions will use chords that all exist naturally within one key.
  2. Roots of adjacent chords within a progression are often more than one letter name apart, and the distance of a 4th or 5th is common, especially at the ends of phrases and song sections.

Let’s start with some definitions you’ll find to be important:

KEY: The key of a song is identified by a tonic note, which is supported by several other notes that all point to that tonic as being the most important. For musicians, it’s often easier to hear it than define it. So play this progression, and pay attention to how the note C seems most musically important: C-Am-Dm-G-C.

ROOT: Most chords will consist of three notes. If you arrange those notes so that the middle note is 3 notes higher than the bottom note, and the top note is 3 notes higher than the middle note (C-E-G, for example), the bottom note will be the root. The root is the note we use to name the chord. So a C chord (C-E-G) is called C because C is the root.

ADJACENT CHORDS: In any progression, adjacent chords are the ones that sit side-by-side within that progression. In C-Am-Dm-G-C, C is adjacent to Am. Am is adjacent to the chord before it (C), and also the chord following it (Dm).

4th, 5th: Think of a C chord (C-E-G), call the root ‘1’ (C=’1′), now count up until you reach 4 (F). That note (F) is a 4th higher than C. Go one note higher (G) and you’ve identified the note that is a 5th higher than C (G).

Take a standard pop song, like Lennon & McCartney’s “All My Loving“, and you’ll see both of those important characteristics in use.

First, most of the chords exist naturally within the chosen key of E major.

F#m  B  E  C#m  A  F#m  D  B7  F#m  B  E  C#m  A  B7  E…

The only one that doesn’t is D. The note D does not naturally exist in E major, so a chord built on D is a non-diatonic chord, a term that simply means that its a chord that was pulled in simply to add harmonic interest.

Second, you’ll notice that the start of “All My Loving” uses chords that are a 4th or 5th away from each other (F#m to B, B to E), and it happens again near the end (B7 to E).

Musically speaking, using chords that are a 4th or 5th apart is a strong organizing feature of good progressions. It makes the key much clearer, and provides a musical anchor that prevents the progression from sounding disorganized or random.

If you hear songwriters talking about the circle of fifths, it’s because it’s such a powerful tool for ensuring that the key is clearly identifiable. “All My Loving” demonstrates how important 5ths become near the end of progressions.

(It’s a topic for another post, but it’s also worth noting how important the interval of a third is between adjacent chords in this song: E to C#m, C#m to A, A to F#m, and so on. A kind of “circle of thirds”.)

If you find that the chords you’ve been working out for your song sound a bit too random or confusing, most problems can be solved by making sure that most of your chords come from one particular key, and that the interval of a 4th or 5th figure prominently especially toward the ends of musical phrases and musical sections within the song.


Gary EwerWritten by Gary Ewer.  Follow Gary on Twitter

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