In the following article we’re going to dabble in some basic music theory for guitarists and explain the relationship between chords, and how to establish what chords go together. So, if you are currently using trial and error to find chords to add to your song ideas, stay tuned! This should really help you.
All music has a key, and all keys a corresponding major scale. The notes included in the major scale are the same as the root notes of the chords within that key. Determining the ‘quality’ of the chord e.g. major, minor, diminished etc. is done by stacking thirds (moving up three scale degrees) above the root note, and then identifying the intervals between the root and other notes included in the chord.
While the explanation above will help you determine the chords within a specific key, allowing you to play chords that are ‘in key’ there’s plenty more to understanding how chords work together.
And, while many guitarists might be turned off by music theory in favor of ‘feel’. The two can exist in perfect harmony (pun intended).
After all if you understand how a language works chances are you will learn to speak it more fluently, as we’re about to find out.
Keys and Chords
When trying to work out chords that go together, there are two main areas to address.
First, what are the letter names of the chords, or root notes of the chords within a given key, and secondly what quality the chords are e.g. major, minor, diminished, augmented etc.
Working out the letter names of chords within a given key is actually fairly straight forward.
As we discussed in the introduction, the notes in the major scale represent the root notes of the chords within a key.
All major scales are built from the 12 available notes used in western music:
The Chromatic Scale
These 12 notes are known as the chromatic scale and all major scales take 7 notes from this set of 12 notes in the following sequence:
* Continuing the sequence results in the next being a half step or semitone, which would be the tonic note again.
The key of the scale taken is determined by the tonic, which is the first note in the scale, and the formula starts on the tonic.
The E major scale for example, would then look like the example below, as the tonic or first note of the scale is E and the notes included in the scale follow the sequence above (whole, whole, half, whole, whole, whole).
Each note of the major scale has a number, which we call a scale degree, as shown in the table below:
E Major Scale
The D major scale, for example, would use the notes and scale degrees used in the table below.
D Major Scale
Once we understand scales we can begin to build chords from them.
There are three ‘types’ of chords.
When most people refer to chord types they are thinking in terms of minor, major etc. But this is actually the chords ‘quality’.
Chord types refer to how the chord is built.
There are 3 ‘types’ of chords. Triads, 7th chords, and extended chords.
We will deal with triads, but if interested you can read more about 7th and extended chords here.
What’s a triad?
A triad is a chord built from three notes.
If you are wondering why many chords on the guitar seem to include more than three notes, it is because the notes are repeated e.g. a D Major chord includes the open D string, and another D on the third fret of the B string.
Triads are built from scale degrees and major and minor chords follow specific chord formulas. So for example a major chord is built from the first, third and fifth scale degrees of the corresponding scale.
When chords are built this way it is referred to as stacking thirds, as there are three scale degrees between each note included in the chord, and when counting scale degrees the first note is counted as 1.
Here’s an example:
D Major Scale
Based on this we now know a D major chord uses the notes D (root), F#(third scale degree), and A (fifth scale degree), or root, third and fifth for short.
The third is important. It determines if the chord is major or minor by the number of notes between the root and the third.It’s important to remember, we don’t count the notes of the scale when counting the notes between the root and the third, instead we count the actual notes between them. With this in mind we can see the F# is four notes after the D: E.g. D, D#, E, F, F#
This is known as a major third interval and because this is the interval between the root and the third, the chord is therefore major.
When we flatten the third by a half step we end up with three notes between the root and the third, making this interval a minor third which makes the chord minor.
You can read more intervals here if interested.
And that’s really all there is to how triads are built. Once you know the formula you can work out the notes in any major or minor triad relatively easily.
Chord Numbers (The Nashville Numbering System)
Unless you have memorized the notes in any given scale and the formulas used, it’s obviously not ideal to count the notes of the scale to work out the quality of a chord.
With this in mind, it’s simpler to focus on established patterns that occur within music.
For example, in all major keys the first, fourth, and fifth chords are always major. The second, third and sixth are always minor and the seventh, which is built upon the 7th scale degree is diminished.
In minor keys the I, IV, and V chords are minor. The III, VI, and VII are major and the II is diminished.
The tables below shows this more detail:
So far this should all make sense with regard to chords that are within a given key, but when discussing chords, especially as part of a chord progression, we use roman numerals, as follows:
Nashville Numbering System
This system known as the Nashville Numbering System was first developed in the 1950’s to simplify the naming of chords within a sequence. The chords that correspond with the roman numerals in the table above are named by the number the roman numeral represents.
For example, the D is I chord. The E is the II chord, F# the III chord, G is the IV chord, and so on.
Understanding which of these numbers in combination work well together is key to understanding what chords go together.
For example the I, IV, V chord progression is a particularly well-known three chord formula that has been used extensively throughout music. And, one thing you might notice right away if you look back at the tables above, is I, IV, V are all major chords.
It’s important to understand when playing chords within a key, we use the major scale of that particular key. It doesn’t change when we play the II or IV chord for example.
So for example, if in the key of D again, if we are stacking thirds we are only using the notes within the key of D, e.g. the D major scale.
D Major Scale
With this in mind the I chord uses the notes D, F#, and A, making it a D major chord. If we take the II chord however, we have the notes E, G and B making the chord minor.
If, instead we were referring to the E major scale the notes would instead be E, G# and B) making the chord major.
Chords, when played as part of a progression such as I, IV, V take on specific moods within chord progressions e.g. the I chord is the root and therefore when we return to the I chord the progression resolves.
While the V chord adds tension, and feels like it must return to the I to resolve the chord progression.
Each chord in this regard has a function within a larger context, and is used to define the mood or feel of a larger chord progression, largely due to how specific notes color a specific chord. This is why some formulas work more effectively than others for specific genres.
If considering chords in this way there are six harmonic functions:
These can be arranged into three specific groups: Tonic, Subdominant and Dominant.
- Tonic chords, are the chords progressions resolve on and therefore create a mood of stability.
- Dominant chords on the other hand create the opposite mood, resulting in tension and a need to resolve.
- Alternatively subdominant chords lie somewhere in the middle, taking a little of both but feeling less intense.
You can try this yourself playing a simple I, IV, V chord progression and noting the mood of each chord within the context of the chord progression. Over time, especially when writing music you begin to notice that music is built upon a pattern of tension and release with everything really being about the journey to resolving the chord progression.
Now that we understand how to establish the letter names and qualities of chords within a specific key, understand how chords are represented by numbers, and the mood or role each chord plays within a chord progression we’ll finish this article with a look at some of the more common chord formulas used in music.
I, IV, V
Tonic > Subdominant > Dominant
The I, IV, V chord progression is foundational, and feels familiar because it has been used extensively.
It typifies tension and release within music, and is used to build the 12 bar blues (I, I, I, IV, IV, I, I, V, V, I, I) that more or less lead to modern pop and rock . Wild thing by the Troggs is a well-known example of I, IV, V.
I – V – VI – IV
Tonic > Dominant > Sumediant > Leading tone
Perhaps the most overused chord progression in western music, the sheer number of songs written using the I – V – VI – IV is remarkable.
In fact, if you haven’t seen ‘four chords’ by the Axis of Awesome, I have added it below and recommend you watch it. If you are unfamiliar with this ‘sensitive’ chord progression you will be amazed at just how many songs utilize it.
I–VI–IV–V (The 50’s progression)
Tonic > Sumediant > Leading Tone > Dominant
Dating back to early classical music, the 50’s chord progression, as the name implies really took hold during the 50’s. In fact, the I–Vi–IV–V typified pop music of the 50’s and 60’s, particularly doo wop. Elton John’s crocodile rock is a good example.
I, V, VI, VII
Tonic > Dominant > Sumediant > Leading Tone
The I, V, VI, VII has been used in music since the 50’s but is perhaps better known for its role during the 90’s in songs by artists such as Aerosmith and Kelly Clarkson.
Knowing what chords go together well, comes down to understanding how to identify the chords within a given key, the quality of the chord and its role with regard to the mood it helps create within a chord progression.
And while you may prefer to write music in a less technical way, consider going back and looking at the music you might have previously written, you might be surprised just how much of the information above you have naturally used when composing music. Feel will always be the most important element when it comes to writing music, but knowing a few shortcuts doesn’t necessarily need to make your music feel more sterile, and in fact may unlock musical directions you hadn’t considered previously.