Major Diatonic Triads / Music Theory Lesson

Author: sleepfreaks

The Most Fundamental Chord Group – Diatonic Chords

We have taken a look at various chords in our previous articles.
Though many other chords exist, the chords we have learned up until this point
are more than enough to make simple songs (complicated doesn’t = better in song writing).

From this point on, we will be focusing on “how to choose chords to create a song”.

Perhaps you have heard of the phrase “diatonic chords”?

Simply put, they are “a compatible group of 3 note chords (triads) that can be used when making a song in a particular key”.

Each key has a diatonic chord group with 7 triads and 7 4-note chords.

The biggest characteristic of diatonic chords is that
they are made using ONLY notes found within the scale of the key.

Because of this, for example in a song in the key of C major, C major diatonic chords are easy to use and create a song with.

We will begin taking a basic look at diatonic chords, with a particular focus on major diatonic triads in this article.

Where Does “Diatonic” Come From?

The word “Diatonic” is related to the “diatonic scale”.

Diatonic Scale = A scale made up of 5 whole steps and 2 half steps in each octave

Though it may seem difficult in words, simply put “do re mi fa so la ti do” is one of these scales.

We want you to think back to the major scale and minor scale for a moment,
but both of these contained 5 whole steps and 2 half steps within them.
This means that both major and minor scales are encompassed as diatonic scales.
(other various scales are included, but these are the two most popular)

Most Western music is generally written in a major or minor key,
and because diatonic chords are made up notes only found in that scale,
they fit incredibly well together.

And of course, there are diatonic chords that are not major or minor chords.

Diatonic Triads

Lets think about this in the song writing process.

For example, maybe we want to make a song in the key of C major.


In this case, generally you would create a melody using notes from the C major scale.


We have made a sample melody in using notes from the C major scale below:


By knowing the diatonic chords, it becomes much easier to choose chords that will fit well with a given melody line.

Forming Diatonic Chords

To better understand diatonic chords, lets begin forming them.
First, we’ll start with a C major scale.


With C as the starting point, we will skip over a note at a time to stack 2 more notes on top of it.
In this case, this gives us E and G. This is easy to copy and paste in a DAW as well.


Like this, we have put together a C major chord.
Apply this process to the notes D, E, and so on.

By doing so, when you reach G you will notice there is a missing note on top.Though you can bring one up from the bottom, if you find this process confusing at first you can start by sequencing 2 octaves of the C major scale instead.



When you finish this process up to B, lets take a look at how to group the completed 3 note chords.



These are the diatonic chords found in C major.

If you’ve been keeping up with our previous articles, you may already the type of chords that we have here, but just to make it simple, lets move the root of all the chords to C.
※ All of the chords have been moved to make the root / lowest note C.


Because the chord on the furthest left is C major, we can easily see whether each chord is major, minor, or diminished (triad).

Lets return them back to their correct places and see what each diatonic chord is classified as.



From the left we have

major / minor / minor / major / major / minor / diminished (triad)

This order of chord types applies to every other major key.

Example:D Major – Diatonic Chords

Using Diatonic Chords According to the Key

As mentioned earlier, lets try placing C major’s diatonic chords to our Key=C melody.


As seen, though we used only the diatonic chords from the key of C major,
the resulting sound works wonderfully and moves smoothly.

Of course, there are various methods in how the chords are selected/arranged,
but by first knowing diatonic chords, it makes this process much easier and can be applied in various situations.

In addition, when scale notes are given numbers, there comes a specific rule when memorizing diatonic chords.
We will take a look at this in a future article, so be sure to have this concept down first!

In our next article, we will be taking a look at 4 note diatonic chords.

Article Writer: Kazuma Itoh

講師 伊藤
After moving to the USA at 18 years of age with a scholarship from Berklee, he completed a 4 year study focused on song writing and arranging there.
Using this knowledge, he works across a variety of fields from pop music, film music, and more.