Keys and Chord Theory for Songwriters

There are twelve keys in modern music: C, Db, D, Eb, E, F, F#, G, Ab, A, Bb, B.  My goal here is to sidestep as much technical music theory as possible, and get down to a list of chord choices in these keys. Every key works in the same way, it’s just that the chord families are relatively lower or higher in pitch, depending on the key.

For example: Playing C, Am, F and G has the same sound as playing G, Em, C and D. The difference is only one of relative pitch. Try it and see. Or, if you play guitar, play the first progression in C and then put a capo on your guitar and play the exact same thing. All that has changed is the relative pitch.

So, basically, if you can understand how chords work in one key, you can understand how they work in every other key too.

The fundamental chords in a key are derived from the major scale of that key. In the key of C, the notes of a C major scale are:

C, D, E, F, G, A, B

SEE THAT THERE ARE SEVEN NOTES. Each chord shares three of the notes from the major scale. That will give us seven chords that we can categorize by number. In the Nashville number system, which is a convenient way of charting out chord changes, each chord gets a Roman numeral. Without diving into the theoretical “why”, let’s list these chords.  (m=minor)

I   IIm   IIIm   IV   V   VIm   VII

C  Dm   Em    F     G   Am  G7

For simplicity’s sake, we can forget the VII chord for now and wind up with:

I   IIm   IIIm   IV   V   VIm  

C  Dm   Em    F     G   Am 

This gives us three major chords and three minor chords (m).

The I  is called the tonic, the IV is called the subdominant and the V is called the dominant. There have been hundreds of thousands of songs written with only the  I, IV and V--C, F and G in the key of C.

If we shift our thinking to minor, we can superimpose the same relationship (I, IV, V) using the VI, IIm, and the III, which is now major rather than minor. The VI becomes the tonic, IIm chord becomes the subdominant and the III chord becomes the dominant. 

In either case, all of the other chords can also be used to create a progression.  For example, here is a chord progression using the I as the tonic:

C-G-Am-F

C-G-F-C-Dm-C

Here is a chord progression using the VI as the “tonic”, yet still technically in the key of C. This is common in songs that are in minor keys.

Am-F-G-Am

Dm-Am-E7-Am

Just about every minor song is based around the VIm chord. It becomes the tonal “center”, so in C, the Am would be assigned the status of “tonic”, even if just for conceptual purposes. In each key, the VI chord is also known as the relative minor. In C, the root of the  VIm chord (A) can be found by moving a step and a half down from the C note, which is the root of the major scale in C.

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A lot can be done with just those six chords, but there are more possibilities besides those major and minor chords, even if we stick to the same six basic chords for now. The first option we have is to alter the IIm, IIIm and VIm chords. We can choose to make any one or even all of them major if we choose and if it fits the musical purpose of our song melody.  For example, we could make all the chords major and end up with this:

C-A-D-G-C

Or

C-E-A-D-G-C

We can choose to keep some of the original minor chords minor and just change one or two to major chords. For example:

C-E-Am-C

F-A-Dm-G

Still sticking with the same six chords, we can also make the IV (subdominant) and the V (dominant) minor if we so desire. For example:

C-Dm-Fm- C   Or

C-Gm-C7-F

Fm-C-D-G

We could also make the IIm and IIIm into a major chord and get this:

Am-D-Am-E7-Am

Starting with our six chords, we have added five variations, giving us eleven possible chords in the key of C, using major and minor possibilities. And we haven’t even looked at that VII chord we have ignored so far.

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While most popular music organizes itself around these basic six chords, there are still a lot of variations and options that we have to look at. These chords fall outside the notes of the major scale but are commonly used. Let’s look at three useful ones right now. They are the bVII, the bIII and the #V.  All get a lot of use, especially in rock, but also in genres as diverse as bluegrass and hip hop. Music, regardless of style, still uses the same elements, so this information will serve you in creating music in the style you want to write in.

Let’s look at the first one—the bVII. In C, it would be a Bb chord—one whole step down from the C, or tonic. A common progression using the bVII would be something like:

C-Bb-F-C

We’ve all heard that a million times.

The next is the bIII. In the key of C it would be an Eb chord.  A common progression would look like this:

C-Eb-F-C

It is often used along with the bVII chord, giving us chord progressions like these:

C-Eb-Bb-F  or C-Bb-Eb-F

Ok. So let’s look at the #V, which is a half step up from the normal V dominant chord. It will be a G# in the key of C. It often functions as a chord that is moving toward the V, but it can also stand on its own as a part of a general chord progression. As a chord moving toward the dominant, it might be used like this:

C-Am-G#-G-C  or F-Dm-G#-G-C

Without resolving to the V chord, it could be used like this:

G#-Eb-Bb-F-C or Fm-Bb-Eb-G#-C#-G-C

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Now, we have 14 different chord possibilities built around the basic key of C. So what about this VII chord that we have avoided like the plague? Well, it has its uses at times. As an extension of a V7 chord, it can become a diminished chord with the root of B. Like this:

C-Bdim-Dm7-C

It can also be used as VIIm to move your progression to a VIm chord via a III chord. Lennon/McCartney did this in “Yesterday”:

C-Bm7-E7-Am

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While this discussion certainly leaves out some odd changes, it covers almost everything a songwriter needs to create good chord progressions with movement, surprise and continual interest. I have purposely left off the concept of modulation into different keys for now. Still, this information offers a multitude of possibilities to create interesting chord changes to build songs and melodies around.

Last, I would like to list all these chords in the common keys as a reference. Experiment with using different combinations. Listen to the “color” of each chord. Feel the particular tension each chord exhibits and note where it wants to move harmonically to your ear. All these chords want to eventually get back to the I chord—the tonic chord of the key you are in. Each has a sort of personality and tension as it seeks where it wants to move harmonically.

In the following list, remember that the minor chords can also be turned into major chords. The IV and V chords can be converted to minor.

I    IIm   IIIm   IV   V   VIm   VII  bVIII   bIII  #V

C   Dm   Em     F     G   Am    G7   Bb       Eb     G# (Ab)

D   Em    F#m   G    A    Bm    A7   C         F       Bb

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

F    Gm   Am   Bb   C    Dm    C7   Eb       Ab    Db (C#)

G    Am   Bm    C    D    Em    D7   F         Bb     Eb   

A    Bm    C#m   D   E    F#m   E7   G        C       F

B    C#m   D#m   E  F#   G#m   F#7 A        D      G

An introduction to lyrics—Every song needs a strong idea and a lyric that conveys the essence of that strong idea.