How chords are constructed - and why moving them can have unusual outcomes
What is “add9”? Is the major scale really *that* important?
I observed an interesting thread in a forum over the weekend. The question was about whether a chord shape with open strings could be moved - specifically, could the open C shape be moved up two frets to make D major.
On the one hand, it seems the answer is “yes” because it’s the same shape, so the fretted intervals are the same. On the other hand, there’s at least one open string, which complicates things.
That thread prompted this article, in which I’ll explain how chords are constructed - and, in turn, how you can always know what notes/intervals are in a chord.
I’ll start with a spoiler: if you move the open C major chord shape along two frets, you don’t play D major. You’re actually playing D (add4) (add9) (no5).
Let’s explore why that’s the case.
How chords are constructed
The major scale is the basis for Western music. Although new guitar students often learn chords and scales as separate things, they’re not. The notes inside a chord, and the chords inside a key, are based on the major scale. Indeed, other scales are also based on the major scale.
It’s become popular for beginners to learn the minor pentatonic scale as their first scale, but I no longer agree with this principle. The major scale should be taught first. Otherwise it’s like trying to build a house while starting with the windows - you must lay the foundation first!
The major scale has a simple formula:
W W H W W W H
“W” means “whole tone”, or two frets.
“H” means “half tone” or “semitone”, or one fret.
To put this into practice, pick a starting note then move 2 frets, 2 frets, 1 fret, 2 frets, 2 frets, 2 frets, then 1 fret and you'll be one octave from where you started. (If you have a guitar nearby, try this now.)
You’ve just played the major scale, on one string.
So how does this relate to chords?
An introduction to intervals
Each note in the major scale is a specific interval. “Interval” is a term that denotes where in the scale that particular note sits, or the relation of one note to another. Let’s use C major for this example - it has no sharps or flats, the notes in the C major scale are simply
C D E F G A B C
Intervals are described in numbers. If you’ve ever heard people talk about “the third” or “flat seven” they’re referring to the intervals. It sounds complicated at first but actually intervals never change, they explain where a note sits within a scale.
In the C major scale, C is 1 - because it’s the first note.
D is 2 - because it’s the second note.
E is 3 - because it’s the third note.
F is 4, G is 5, A is 6, B is 7, and C is 8.
C is the same note at 1 and 8, but 8 is used to denote that it’s an octave higher than the C we started on.
If you’ve ever wondered what it means when a chord is “add 9” or add 11”, this is why. It’s the same note as its corresponding earlier interval, just in a higher octave.
9 is the 2 interval, an octave higher.
10 is the 3, an octave higher.
11 is the 4, and so on.
If you see C (add 9) it simply means a C chord, with a D note played in the higher octave.
Now we’ve got the major scale and intervals understood, let’s see how they work together to build chords.
How chords are constructed
Chords are built by “stacking thirds.”
This sounds like it might be complicated, but it just means selecting notes that are separated by 3 notes in the scale.
Sticking with C major, the 1 is obviously C, and we know from the previous section that the 3 is E. Starting from E, the next third is G. (You can usually find the third by skipping the next note from your starting position. From C, skip the next note of D and you land on E. From E, skip the next note of F to land on G. From G, skip the next note of A to land on B, which is the 7. The 7 interval is needed to play seventh chords.) Taking these notes, which are all a third apart from the one prior, and making a chord from them is called stacking thirds.
Major chords are built by playing the 1, 3, 5 intervals. So a C major chord has C, E, G.
Let’s take a look at the open C major chord (I’ve taken this image from Chordbank):
This image shows which fingers to place in which frets, and is how most guitarists are taught. But it doesn’t explain what the notes or intervals are, so the construction of the chord remains a mystery.
The third finger is playing the note C, or the 1 interval. The second finger is playing the note E, or the 3 interval. The open G string is the 5 interval. The first finger is playing the note C, or the 8 interval. The open high E string is the 10 interval (an octave of the 3).
As you can see, we have the 1 3 5 intervals present, plus a couple of octaves. Thus, it’s a major chord.
If you shift this pattern up two frets, at first glance it might seem like you’re playing D major. After all, it’s the same shape, right?
Well, sort of. Your 1 3 and 8 are in place, but the open G string throws a spanner in the works.
The D major scale is D E F# G A B C# D
Therefore, the notes inside a D major chord are D F# A.
That’s why if you play the open C chord shape and slide it up two frets, it’s not D major.
It’s D (add4) (add9) (no 5).
The open G string is the 4, the open high E string is the 9, and there’s no A note (5).
To make it a true D major, we need to find that A. Let’s take another look at that C chord:
I’ve annotated the image to show where the 5 is - to replicate this shape as a closed chord to play a true D major, we need to mimic the open string. Basically, as you move that shape along the fretboard, you need to fret the note in that position relative to the other notes.
D major would look like this, in tablature form:
E: x (or 2, if barred)
B: 3
G: 2
D: 4
A: 5
E: x
Here’s a picture of yours truly demonstrating it. My pinky plays the D (fret 5 of the A string). My ring finger plays the F# (fret 4 of the D string). My first finger plays the A (fret 2 of the G string). My middle finger plays the D (fret 3 of the B string).
This is the D major chord, played using the C major shape. We’ve got the intervals 1 3 5 8. If you want to also include the high E string, flatten your first finger so it’s fretted in fret 2, and you’ll add the interval 10 as well (10 being the octave of the 3, or F#)
Crucially, this is now a closed chord - there are no open strings. This means we can move this shape along the fretboard with no problems. Move it up two frets from here and it’s E major. One more from there, F major. Two more, G major.
Creating a practice routine
That, in a nutshell, is the theory behind chords. Learn the major scale, and look at the notes of the scale in your chosen key to know which notes need to be in a given chord.
If you’re playing a major chord, you need the interval 1 3 5.
For a minor chord, flatten the 3 (find the 3, then go one semitone down. In C, the 3 is E so flat 3 would be D#).
If there’s a note from a higher octave it’s represented by a higher number (e.g. add9) and you get there by simply continuing to count from 8. Like this, using C major:
C - 1
D - 2
E - 3
F - 4
G - 5
A - 6
B - 7
C - 8
D - 9
E - 10
F - 11
G - 12
A - 13
B - 14
C - 15
(Caveat: convention is to stop at 13. So 14 and 15 technically are permissible, but you're unlikely to encounter them. I just included them for completion of the scale so we didn't end at A 13.)
To practice this, I suggest playing a major scale and simply count each note as you play - 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, and so on. That subtly embeds the intervals in your mind. Alternatively, count like this: 1, 2, 3, 4, 5, 6, 7, 8, 2, 3, 4, 5, 6, 7, 8. The goal is to train your memory to know where the intervals sit under your fingers - the notes will change from one key to another, but the intervals are always located in the same place. The easiest example of this is power chords: whatever fret you start in, you know that the 5 is located one string down and two frets along, and the 8 is directly beneath that 5.
With this in your memory, you can be playing a note and decide you want the flavour of a particular interval - let’s say a 6 - and know exactly where to find it in relation to your root note. This opens the door to total freedom as a player.
I also suggest playing the major scale on one string, horizontally. So to play C major, start on the 3rd fret of the A string and follow the WWHWWWH formula (frets 3, 5, 7, 8 ,10, 12, 14, 15).
Finally, write out the major scale for each of the 12 keys and identify the 1 3 5 intervals from each. That gives you the notes for the corresponding chord, and you can cross-reference to check it’s correct. For example, write out the B major scale and then make the B major chord by identifying the 1 3 5 intervals from the scale.
As an aside, knowing the major scale and intervals also unlocks what chords should be played in every key - whether major, minor, or diminished. That’s a lesson for another day but it reinforces the point that the major scale is the foundation for Western music, and getting familiar with it is a huge advantage.
Has this lesson helped you? Let me know with a comment, and if there’s a particular lesson you’d like me to do in future I’m open to suggestions. If you’ve enjoyed it, please subscribe and let your guitar-playing friends know about this Substack too.