A Quick Introduction to Chord Relationships

Learning about the relationships between chords in a key can pay off many times over for a songwriter.

Let’s take a quick look at the common chords in major keys. We’ll be using images for each chord to help you imagine and remember one model of how they relate to each other.

The Six Common Chords in a Major Key

We can label the chords in a key with Roman numerals. Think of each Roman numeral as representing a chord with its own identity and characteristics.

There are six common chords in major keys, labeled I, ii, iii, IV, V, and vi. An uppercase Roman numeral means a major chord. Lowercase means a minor chord.

Here’s an example in the key of C major, along with images we’ll explain as we go. A complete list of all major keys can be found at the end of the post.

Let’s take a quick look at each chord.

The Home Chord

The I chord acts as home in a song. It’s a place to start and a place to return to. In a major key, the name of the I chord is the name of the key.

Play this chord to ground your song and to resolve tensions. You can also purposely delay it to create tension.

The Magnet Chord

The V chord is like a magnet pulling us back to the I.

Together, the I and V help establish that we’re in a particular key.

You can use the V chord to create tension and a desire in the listener for resolution. You can also avoid it to create more ambiguity.

The Neighborhood Chord

Think of the IV chord as our immediate neighborhood. It takes us to a new location, but not too far from home (which is the I chord).

You can use the IV as a temporary destination or as a waypoint on the way to the V.

You can also move directly from IV to I for a softer landing.

Combining the I, IV, and V

The I, IV, and V chords together make up what I call the core chords of a major key. They strongly establish the key and can technically harmonize any major key melody.

You could build a whole career in the blues or folk music by mostly sticking to these three.

Here’s an illustration of their relationships:

The red line indicates the strong magnetic pull back home of the V. The black lines represent something expected but not as strong.

Keep in mind that in popular musical forms, any chord can follow any other chord. These illustrations are just emphasizing some of the most expected transitions.

Don’t forget: as a songwriter, you can always subvert expectations as well as fulfill them.

The Shadowy Twin Chord

The minor vi chord brings us to new and more mysterious places. I liken it to a shadowy twin of the I chord.

You can use it to prolong the I and create interest. It can also function as a new location further away from home. As an example, try starting your chorus on the vi.

The vi is also called the “relative minor” of the I. Playing the common major key chords but emphasizing the vi chord might actually put you in a minor key with the vi as home.

You can play with this ambiguity.

The Tunnel Chord

The minor ii chord can intensify the pull from the V to I as part of a “magnetic tunnel progression” (ii-V-I).

It can also be part of walking tunnel progressions like I-ii-iii or iii-ii-I. These create a recognizable sense of movement that’s clearly in key.

Another interesting aspect is that you can substitute the ii wherever you have a IV in your progression.

They share 2 out of 3 notes.

The Moody Twin Chord

The minor iii chord can act as a kind of moody twin to the I. Maybe I should call the I, vi, and iii chords “triplets”, but “triplet” has another meaning↗(opens in a new tab) in music!

Here they are:

In theory, the vi or iii can be substituted wherever a I chord appears in your progression since they share 2 out of 3 notes with the I.

You can use the iii chord itself to take us to moody, dark, and unexpected places. It can be trickier to use well than the other major key chords, but it’s worth experimenting with.

Tying them all together

Here’s one way to imagine the relationships between all six common chords:

Remember, in popular music any chord can move to any other chord. The black arrows just show us some of the things our listeners might expect.

The red arrows show an extended magnetic tunnel sequence. Listen to this progression in the key of G major to get a sense for the familiar momentum of the tunnel:

| iii | vi | ii | V | I |
| Bm  | Em | Am | D | G |

You can play with these chord relationships in any key. Here’s a table with all of the major keys:

Next Steps

We’ve looked at one framework for thinking about chords. It can help you quickly create chord progressions that work, but don’t think of these as rules you have to follow.

Once you’ve internalized them, you can start pushing their boundaries.

For a more technical dive into these relationships with examples, you can read my post on harmonic functions for songwriters. Or you can explore the metaphors in this post further through a series of exercises that help you get familiar with one chord at a time.

Finally, you can also check out my quick introduction to minor key chord relationships.