Extended Chords: How to Add Color to Your Songs with Extensions

Chords are the pillars that hold up your songwriting. Along with rhythm and melody, harmony is one of the most fundamental parts of music theory.

The sound of your chords says a lot about the identity of your music. Simple harmonic structures work just fine, but rich chords can make a song stand out.

Adding extensions to your chords is how you bring that richness into your tracks.

In this article, I’ll teach you to build chords with extensions and show you how to use them to take your songs beyond the triad.

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What are extended chords?

Extended chords are vertical sonorities with extra color tones in addition to their basic triad of chord tones.

Extended chords are vertical sonorities with extra color tones in addition to their basic triad of chord tones.

If that sounds complicated—don’t worry. I’m about to go over everything you need to understand extensions from the ground up!

Chord construction

Adding extensions starts with building chords.

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If you need a refresher, check out our article on how to build chords to jog your memory.

The basics are pretty simple. You build chords by stacking 3rds on top of each other. The relationship between those intervals and the root note determines the quality of chord.

You need to keep track of the scale degree and quality of each interval to identify the chord.

For example, If you stack some thirds up on a staff, you’ll get a snowman:

By identifying the intervals, you know you’re looking at a major triad.

So far so good.

Let’s take it a step further.

If you’ve been practicing your ear training, you’ll probably know by now that some chords contain more than three notes.

But what notes can you add to your chord? How does it work and how will it affect your sound?

7th chords

You know about the four chord qualities you can create with three notes. Major, minor, diminished and augmented. What happens when you add one more to the mix?

To get started, try adding a third above the last note in your snowman:

If you evaluate of the intervals of each note in relation to the root you have a major third, a perfect 5th, and a major 7th.

That identifies the chord as a major seventh.

However, every time you change the quality of an interval, the quality of the resulting chord will also change.

If you try all the combinations, that gives you:

• Major 7th
• Dominant 7th
• Minor 7th
• Half-diminished 7th

For now I’ll focus on the first three, since they’re the most commonly used.

Adding these four note chords to your vocabulary gives us a pretty big range of options!

More notes?

Four note chords still aren’t really considered extended.

Since the interval relationship of all four notes has an impact on the quality of the chord, we call the first four notes in a chord the chord tones.

Since the interval relationship of all four notes has an impact on the quality of the chord, we call the first four notes in a chord the chord tones.

But let’s go back to the example add another third to your snowman (which is starting to look like more of a totem pole):

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If you evaluate this note’s relationship to the tonic, the result is different. It’s the second degree of the scale, but an octave up.

This is the 9th. It’s the first of the extensions.

Extensions are notes that stack up as thirds on the totem pole, but don’t have the effect of changing the overall quality of the chord.

We can add these notes to a chord for colour, but their interval quality won’t change the basic structure of the chord.

The resulting chord in this case? C Major 9.

Listen to the colour the 9th gives the chord. There’s a pleasing tension from its close proximity to both the root and the third. The chord sounds richer, but it’s still a major 7th.

So far so good. But there are more extensions to go!

Available extensions

For the next third you stack on to your snowman, the result isn’t quite the same.

Instead of richness and sophistication, this next extension adds an uncomfortable grinding dissonance. Something about the 11th you just added doesn’t agree with the C major 7th chord.

So how can you tell which extensions to use? The answer lies in avoiding the dissonant quality you accidentally created.

Dissonance is a subjective term whose meaning has evolved considerably throughout music history—but here I’m talking about a very specific kind of dissonance.

The rule of thumb is that adding extensions that create a dissonant minor 9th interval with one of the chord tones isn’t allowed.

The rule of thumb is that adding extensions that create a dissonant minor 9th interval with one of the chord tones isn’t allowed.

To use the 11th, we’ll have to alter it. The only accidental we can add to avoid creating other minor 9ths is a sharp.

Adding the sharp will give you Cmaj7#11, a pleasantly complex sonority that seems both stable and tense at the same time.

Adding the sharp will give you Cmaj7#11, a pleasantly complex sonority that seems both stable and tense at the same time.

The #11 is the same pitch class as the #4. If that’s ringing a bell, it’s because the raised 4th scale degree is the characteristic note of the Lydian mode.

In fact, if you spell out the chord with all of its extensions and write them in their simplest form, you can see that a chord with all of its extensions is made of all the notes in the corresponding scale.

1-3-5-7-9-11-13 = 1-3-5-7-2-4-6

This is known as the chord/scale relationship. You don’t have to memorize every single available tension if you’re already familiar with the modes of the major scale.

The relationship between modes and chords tells you which extensions you can add to a chord, but also which scale to play over it while improvising. Pretty cool!

Writing with extended chords

If the giant stack of thirds you just created looks clunky at this point, you’re absolutely right.

In the real world, extended chords won’t always contain every single possible note and they probably won’t be voiced as a blocky vertical sonority.

In the real world, extended chords won’t contain every single possible note and they probably won’t be voiced as a blocky vertical sonority.

In most cases, you’ll choose to add only a few extensions—a 9 here or a #11 there for emphasis. To make your chords even more economical you can even omit a chord tone or two if they don’t contribute to the harmony. It’s up to you!

But now that you know the relationship between modes and extended chords, you can use extensions anywhere you might consider using the associated mode.

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If you need a refresher, check out our article on music modes.

Here’s the basics: you can think of the character of the modes like colours on a scale from light to dark.

The more raised notes that a mode contains, the “brighter” it seems. The more lowered tones, the “darker.”

It’s the same principle with chord extensions. You can instantly make a Major 7th chord sound brighter by adding the #11 extension.

Or lighten up a minor chord by adding the 13th—the characteristic natural 6th of the Dorian mode!

Extended techniques

Chord extensions are a helpful part of your musical vocabulary. The more you incorporate them into your songwriting, the more you’ll hear how they can bring uniqueness to your songs.

Now that you have some ideas about how to bring more notes into your harmony, get experimenting and see what extensions can do for your music.

Michael Hahn is an engineer and producer at Autoland and member of the swirling indie rock trio Slight.

@Michael Hahn