Building Chords: Major, Minor, Diminished, and Augmented

Introduction

This lesson will introduce you to identifying chords and building chords of any type. There is not much background you will need in order to get a good understanding of the material explained here. A basic understanding of scales would be ideal, but is not required here.

This is also my first lesson, so please forgive me if I am not clear or concise.

Intervals

We will discuss here the different types of intervals that exist. We will only talk about major and minor intervals here. There are augmented and diminished intervals as well, however I am not sure of the chordal theory that is involved with these intervals.

To begin, we will talk about all types of intervals. An interval is just two notes that have a certain number of semi-tones (or half-steps) between them. So for example, the number of semi-tones between C and D is 2 (C-> C#, C#->D). Below is a scale of all the different intervals and an example.

Number of Semitones	Name		Example

0			Unison		C and C

1			Minor 2nd	C and C#/Db

2			Major 2nd	C and D

3			Minor 3rd	C and D#/Eb

4			Major 3rd	C and E

5			Perfect 4th	C and F

6			Tritone		C and F#/Gb

7			Perfect 5th	C and G

8			Minor 6th	C and G#/Ab

9			Major 6th	C and A

10			Minor 7th	C and A#/Bb

11			Major 7th	C and B

12			Octave		C and C 

Now, the important step to take out of this table is the minor and major 3rds, as well as the perfect 5th. We will be discussing these for the rest of this lesson.

A chord is defined as 2 or more notes played simultaneously (usually at least 3). Most commonly used are major and minor chords (VT Music Dictionary). What we are going to do is break down what we know as a major chord, and show you how this knowledge of intervals will help you build some of your own chords, as well as identifying the name of a chord.

Breakdown of a Chord: C Major

A C major chord is the most common chord that a guitarist will play. Let’s take it apart and see why it is major. C major consists of 3 notes: C, E, and G. Why are these notes chosen to be a major chord? What is it about them that makes it major? Let’s look at the first two notes in this chord: The C and E. Between them, they have 4 semitones ( C->Db, Db->D, D->Eb, Eb->E). Four semitones is listed as being a major 3rd interval. Now, let’s look at the last 2 notes: The E and G. How many semitones are between them? (E->F, F->F#, F#->G) If you guessed 3, you are correct. What interval is 3 semitones? A minor 3rd. Since there are 4 between C and E, and 3 between E and G, we can assume that there are 7 semitones between the C and G. Seven semitones is a perfect 5th.

But what does this all mean? Well, if we look at it from 3rds, we notice that the first 3rd is a major, while the 2nd 3rd is a minor. It just so happens that this pattern is repeated for EVERY major chord in Western music. So whenever you have 3 notes where between the first 2 is a major 3rd and the second 2 is a minor 3rd, that chord is a major chord. Now, let’s move on to a minor chord.

Breakdown of a Minor Chord: A minor

For those of us who love to play in C Major like I do, we know the relative minor is A minor. Let’s break down what’s in an A minor to see what the pattern is for minor chords. An A minor is made up of 3 notes as well: A, C, and E. Let’s do the same analysis we did for the C major. Between an A and C, we have 3 semitones. We have already learned that 3 semitones means this interval is a minor 3rd. For the other 2 notes, C and E, we already did this analysis in the C major chord and we know this has 4 semitones and is a major 3rd.

So, the first 3rd is minor, and the 2nd 3rd is major. This pattern is consistent for every minor chord in Western music. So, if I asked you to build a C minor chord, all you would have to do is choose the minor 3rd above C, and the major 3rd above that note, or a perfect 5th above C. That would mean a C minor is C, Eb(check footnote if you are wondering why this is Eb instead of D#... and yes there is a difference), and G.

Let’s throw a Curveball: 2 Minor 3rds or 2 Major 3rds is what?

You may be asking yourself: There are more combinations of 3rds than just a major and a minor or a minor and a major. What happens if we have 2 minor 3rds or 2 major 3rds. Well, it has to be something, right? Of course it is! Think about out C major scale. Let’s take the weirdest chord of this scale, the Bdim. What notes are involved in this chord? B, D, and F. We have 3 semitones between B and D, and 3 semitones between D and F. Well, we have two minors here… does that mean all diminished chords follow this pattern? Of course it does! Music theory isn’t that complicated: it’s a bunch of patterns.

So if we were to take it the other way, the only chord type left is an Augmented. Let’s BUILD an augmented chord. If I wanted a Caug chord, what notes would I play? First, we need a major 3rd above C. We know this already to be an E. What is a major 3rd above E? Count up 4 semitones. E->F, F->F#, F#->G, G->G# (Check the footnote to see why this is a G# instead of an Ab). So, our Augmented chord has the following 3 notes: C, E, and G#. Great work! We’ve built all 4 kinds of chords.

Conclusion

So, there you have it! That's how you build your basic chords. The most important things to remember here are the 3rd intervals, the perfect 5th interval, and what 3rds make up Major, Minor, Diminished, and Augmented. When you understand these, I would suggest sitting down and memorizing which 3rds are major and which are minor. Good luck!

Footnote:
When we are working with scales, there are certain rules in music theory that we follow when working in a key. In this case, we are talking about 3rds as chordal intervals. A third will always exist as 2 notes with 3 or 4 semitones between them, but another rule is that the name of the note will always be the 3rd note in the scale from the start. As an example, the 3rd above a C will always be an E. Whether or not that’s an Eb, E, or E# is up to the theory. But, you will never see a 3rd labeled as C and D#, or C and F. This is the case where you end up getting an E# or a B#, even though these notes are exactly the same as F and C, respectively.