Guitar Chord Theory – The Complete Guide

Interested in learning about guitar chord theory? Our introductory guide explains (in very simple terms) how to read chord charts, how chords are named and how they are constructed. So if you have ever wanted to understand chord theory rather than simply memorizing individual shapes on the fretboard this guide is for you.

What are chords?

A chord is a combination of three or more different notes played at the same time, usually to support a melody.

This doesn’t mean playing any combination of three or more notes on the guitar will sound musical. But, technically, provided you are playing a combination of three or more notes at the same time, you are playing a chord.

What are Arpeggios?

An arpeggio is simply a chord with the notes played sequentially e.g. one at a time, rather than at the same time, as in when strummed.

Triads, sevenths and extended chords

Chords can be categorized based on the number of notes they are constructed from and include triads, seventh and extended chords.

Triads

Triads consist of three notes, the root note, third and fifth.

What are thirds and fifths?
Thirds and fifths are two types of musical intervals. Intervals refer to the ‘musical distance’ between two notes e.g. how many notes are located between two notes.

We’ll explain intervals as we go along as they are foundational to music theory, but for now keep in mind intervals are used to reference the relationships between notes.



There are four types, or qualities of triad. These are known as major, minor, augmented and diminished and are the among the most common chords played on guitar.

Seventh chords

These are simply triads that include the seventh interval from the root note. Again, if this doesn’t make a lot of sense right now, don’t despair, this will become much clearer as we go along.

Extended chords

Extended chords are constructed from more than three notes, with any additional notes beyond the basic triad extending beyond the 7th. This means they include notes from an octave higher. Examples include 9th, 11th and 13th chords.

An octave, if unaware simply means the interval between two notes with one being half or double the frequency of the other. For instance your open E string is technically the same pitch as the 12th fret of your E string but twice the frequency.

What about two note chords?
You may have heard guitarists refer to two note ‘power chords’. These are shapes that include the root note and the fifth interval. They are neither major nor minor in quality as they do not contain a third.

For now it is helpful to understand, two notes played together is considered harmony (the combination of one or more notes played at the same time) but not technically a chord by definition. However, you may see two note shapes referred to as ‘partial chords’.

Open and closed position chords

Most beginner guitarists will start out learning open position chords. These shapes include open strings (unfretted strings) and are played in the first three or four frets.

Closed position aka barre chords do not contain open strings and require the strings to be ‘barred’ across one fret (please see image below), replicating the nut, and preventing any open strings from ringing out.

bare chord

Barre chords can be played anywhere on the neck of the guitar. Typically guitarists tend to learn this once they have mastered open position shapes as they are incorporated in barre chords, along with barring the entire fret closest to the nut using the index finger.

Voicings

Open and closed positions are just two examples of chord voicings e.g. playing the same chord utilizing different positions on the guitar neck.

Keep in mind chords are constructed from notes and when you consider there are only 12 notes in the chromatic scale (the chromatic scale includes all 12 notes in western music) and most guitars have at least 114 frets (21 frets X 6 strings) it becomes apparent that there are many different ways to play chords on the guitar.

How to read chord charts

Chord charts demonstrate how chords are intended to be played.

The following demonstrates ‘A major’ in open position:

A major



The chart itself is essentially an image of the guitar fretboard. The bass strings (heavier gauge strings) are on the left and treble strings on the right. (* some charts may be presented in a horizontal layout)

If you are a right-handed guitarist, this represents the guitar fretboard if you were looking at it directly.

  • The vertical lines represent the strings of the guitar.
    In the chart above the bass strings are shown slightly thicker than the treble strings, this is not always the case and can vary from chord chart to chord chart.
  • The horizontal lines represent the fret wires.
  • The thicker black line shown at the top of the chart indicates the nut.
  • The black dots represent the finger placement on the fretboard.
    The root note is sometimes shown as a white dot with black outline but as in the chart above, not in all cases.
  • The ‘X’ above the first fret indicates the string is not to be played.
  • The ‘O’ indicates the string is to be played but is unfretted, or in other words it is an open string.
  • Lastly, the numbers at the bottom of the chart represent the fingers used to fret the notes.
    In this case the first (index finger), second (middle finger) and third finger (ring finger) are used to play the A major chord. Some chord charts include numbers representing finger positioning, some do not.

Chord Fingering

 

Chord charts are not just used to represent open chords. Below is an example of a A barre chord.

A Major Barre Chord

Being a closed position shape, the 5th fret is barred which is indicated by the curved line above the fifth fret, you will also notice the absence of the thicker black line representing the nut. You will also notice the number 1 used on the notes played at the fifth fret. This means all the notes that align with the fret are fretted using the first (index finger).

Technically only the frets that are numbered are required to be played but it is much easier to simply barre the entire width of the neck.

Unlike an open position shape, the chart itself is a representation of a section of the fretboard taken from the 5th fret, indicated by the ‘5th’ marked on the left side of the chart.

How chords are named

Chords are named based on the root note and the quality of chord. For instance D major  takes its name from the root note which is ‘D’ and the chord being ‘major’.

 When discussing major, minor, augmented etc. we are referring to the chord’s quality, however these are often referred to as chord types. 

Root notes

The root note corresponds with the letter given to the chord name. It helps to think of the root note as the foundation.

For example D is the root note of all D chords (e.g. major, minor, augmented, suspended etc.). C is the root note of all C chord types and so on.

In the majority of cases (but not always) the root note is the first and lowest pitched note. Chords that consist of the root note being the lowest pitched note are called ‘root position chords’.

For instance, when playing an open position D, the lowest note played is the open D (4th string) as the A and low E strings are not played.

D major

In the majority of open position chords the root note will be a note played on one of the bass strings either the low E, A, or D strings.

Another example of this is the open A major. The first string played, is the open A string which happens to be the root note. The low E string is not played.

Repeat notes

Many chords include more than one root note. For example E major consists of both the open low E and high E string being played as individual notes.

E major

It’s not just the root note that can be repeated. All notes used can be repeated. For instance, the following are both C major.

C major is constructed from C (root note), E and G.

C major chord voicings

While the first chord shape contains just the three notes including the open string ‘D’, the second example utilizes 5 notes, however the C, and G are repeated.

Chords that utilize repeat notes are often designed to be easier to play (consider the difficulty of muting the first, 5th and 6th strings in the first example) and tend to sound more expansive, and fuller.

Chord qualities

Regardless of your experience with music, you have likely heard the musical terms ‘major’ and ‘minor’.

‘Major’ or ‘minor’ is a way of describing ‘quality’ and relates to its own distinctive sound, or flavor.

For example, major chords are often described as sounding happy, while minor are often described as sad or serious. The musical intervals they are constructed from define the quality of the chord.

Chords are not restricted to only major and minor however.

The table below shows a list of the four most common qualities and their respective naming conventions.

Quality Suffix Description
Major No suffix used Happy, simple, resolved
Minor min Dark, serious
Diminished dim Tense, dissonant
Augmented aug Suspenseful, unnatural

Other less common qualities include:

Quality Suffix
Suspended fourth sus4, (sus)
Added ninth add9
Minor added ninth m(add9)
Fifth 5, (no3)
Sixth 6
Minor sixth M6m (-6)
Sixth, added ninth 6/9
Minor sixth, added ninth m6/9
Seventh 7, (dom7)
Minor seventh m7, min7, -7
Diminished seventh dim7, dim
Seventh, suspended fourth 7sus4, 7sus
Minor, major seventh m(maj7), m(+7)
Major seventh, flat fifth maj7♭5, maj7(-5)
Minor seventh, flat fifth m7♭5, m7(-5)
Seventh, sharp fifth +7, 7(♯5)
Seventh, flat fifth 7♭5, 7(-5)
Seventh, flat ninth 7♭9, 7(-9)
Seventh sharp ninth 7♯9, 7(♯9)
Ninth 9
Major ninth maj9, M9
Minor ninth m9, min9
Eleventh 11
Minor eleventh m11, min11
Thirteenth 13

Beginning chords

While there are any number of available voicings, when first starting out on guitar, you will start out learning open position major chords (A, B, C, D, E ,F, G) before progressing to minor chords and then on to more complex  shapes such as suspended and diminished.

In many cases learning the major and a handful of minor chords will allow you to play a large number of songs, as many popular songs consist of just three or four chords. I’ve listed some of these below:

Song name Artist Chords used
Get Back The Beatles A, G, D
Twist and Shout The Beatles D, G, A
Bad Moon Rising Creedence Clearwater Revival D, G, A
Wild Thing The Troggs A, D, E
Ring of Fire Johnny Cash G, C, D
Get it on T. Rex E, A, G
Sweet Home Alabama Lynyrd Skynyrd D, C, G, F
All Apologies Nirvana C, F, G
Wanted Dead Or Alive Bon Jovi D, C, G, F
Creep Radiohead G, B, C, Cm
Knocking on Heaven’s Door Bob Dylan G, D, Am, C
The Four Seasons Vivaldi Just kidding 🙂

How chords are constructed

Chords can be constructed using intervals (the distance between two notes) or by using a formula based on the notes of the major scale.

If you are unfamiliar with scales, I’d suggest reading our article on ‘understanding scales’ first as they really are the building blocks of music.

Method 1: formulas and the major scale

We can build chords using the major scale and chord formulas. For example the formula for major chords is:

Major scale formula
1 –  3 –  5

In a practical sense this means we take the first, 3rd and 5th notes from the major scale to build a major chord. These are known as scale degrees and should not be confused with intervals e.g. major third (more on this shortly).

For example the A major scale consists of the following notes:

The A major scale
A – B – C♯ – D – E – F♯ – G♯

The first note (scale degree) is the A, the third the C♯ and the fifth note is the E. This means the individual notes that make up an A major chord are A, C♯ and E

Minor chords on the other hand use the chord formula: 1, ♭3 and 5

This means the third scale degree is flattened by a semitone. This is useful in a practical sense as it means you can make any major chord a minor chord by flattening the third scale degree by one semitone.

Common chord formulas

Below is a list containing the most common the chord formulas.

Chord type Formula
Major 1 – 3- 5
Minor 1 – ♭3 – 5
Diminished 1 – ♭3 – ♭5
Augmented 1 – 3 – ♯5
Suspended fourth 1 – 4 – 5
Added ninth 1 – 3 – 5 – 9
Minor added ninth 1 – ♭3 – 5 – 9
Fifth (partial or power chord) 1 – 5
Sixth 1 – 3 – 5 – 6
Minor sixth 1 – ♭3 – 5 – 6
Sixth, added ninth 1 – 3 – 5 – 6 – 9
Minor sixth, added ninth 1 – ♭3 – 5 – 6 – 9
Seventh 1 – 3 – 5 – 7
Minor seventh 1 – ♭3 – 5- ♭7
Diminished seventh 1-♭3-♭5-6
Seventh, suspended fourth 1 – 4 – 5 – 7
Minor, major seventh 1 – ♭3 – 5 – 7
Major seventh, flat fifth 1 – 3 -♭5 – ♭7
Minor seventh, flat fifth 1 – ♭3 -♭5 – ♭7
Seventh, sharp fifth 1 – 3 – ♯5 – ♭7
Seventh, flat fifth 1 – 3 – ♭5 – ♭7
Seventh, flat ninth 1 – 3 – 5 – ♭7 – ♭9
Seventh sharp ninth 1 – 3 – 5 – ♭7 – ♯9
Ninth 1 – 3 – 5 – ♭7 – 9
Major ninth 1 – 3 – 5 – 7 – 9
Minor ninth 1 – ♭3 – 5 – ♭7 – 9
Eleventh 1 – (3) – 5- ♭7 – (9 )- 11
* (3) and (9) are optional
Minor eleventh 1 -♭3 – 5 -♭7 – (9) – 11
* (9) is optional
Thirteenth 1-3-5-b7-(9)-(11)-13
* (9) and (11) are optional

Many of the formulas may make sense to you even if you are new to music theory. For instance the Added 9th chord, includes (as the name implies) an added ninth note of the major scale e.g. 1 – 3 – 3 – 9

A minor add9th as you may have already guessed uses the same formula, however the 3rd note of the scale is flattened a half step.

Method 2: Using intervals

The chromatic scale

There are 12 notes in western music, and these 12 notes make up the chromatic scale. The scale below is the ‘A’ chromatic scale as the root note and the note the scale begins on aka the tonic is A.

A Chromatic scale with steps

Whole tones and semitones (whole steps and half steps)

The example above includes semitones and half tones. A semitone is the distance between two adjacent notes e.g. A to A♯ is one semitone, equal to a minor second interval. While a whole tone is the distance between two adjacent notes e.g. B to C♯ and is a major second interval.

This tends to make more sense when considering the layout of a piano.

Piano keyboard with steps

The white keys are whole notes e.g. C, D, E, F, G, A, and B. The black keys in between are sharps or flats e.g. C♯, D♯, F♯, G♯ and A♯

  • Sharps and flats are interchangeable e.g. a C♯ is the musical equivalent of a D♭

Only 5 of the 7 notes have sharps or flats, this is why the piano does not feature black keys between each white key. Flats or sharps can be used interchangeably. For example A♯ is the same pitch as B♭.

Why are intervals important?

If we consider an A major chord, the notes used are A, C♯, E.

However, it’s more effective to learn the intervals than the notes themselves if you want to have the ability to construct chords.

The intervals for all major chords are: The first, major third and perfect fifth.

This means you only need to know the intervals of the major chord type rather than the individual notes.

How intervals relate to each other

There are 5 categories of intervals:

  • Perfect: 5th, 4th, unison and octaves
  • Major: 2nd, 3rd, 6th, 7th
  • Minor: 2nd, 3rd, 6th, 7th
  • Augmented: Half step added to a perfect or major interval
  • Diminished: Half step reduced from a perfect or major interval

These categories relate to one another. For example a major interval when reduced by one step becomes a minor interval.

Distance Between Frets/Notes Interval Name
3 Minor Third
4 Major Third

Alternatively, If we lower a perfect interval by one step, the interval becomes a diminished interval, and a major or perfect interval if raised a half step becomes an augmented interval.

Different intervals have different names. Below is a table listing the 12 intervals, the distance between the notes or frets on the guitar neck and the interval name.

Distance Between Frets/Notes Interval Name
0 Unison
1 Minor 2nd
2 Major 2nd (Diminished third)
3 Minor 3rd (Augmented second)
4 Major 3rd (Diminished fourth)
5 Perfect 4th (Augmented third)
6 Tri-tone (Diminished fifth)
7 Perfect 5th (Diminished sixth)
8 Minor 6th (Augmented fifth)
9 Major 6th (Diminished seventh)
10 Minor 7th (Augmented sixth)
11 Major 7th
12 Perfect Octave

If you are wondering where these numbers come from as they don’t appear to correspond with the number of half steps contained within the distance between two notes, that’s because they are not supposed to. Instead, they are based on the musical letters the interval passes through including the start and end note.

For example, a third is called a third because it incorporates three different notes.

Third
A  –  A♯ –  B – C – C

The letters consist of A, B and C

A common misconception
Formulas and intervals, at least in some instances will appear to be the same e.g. the major scale’s intervals are identical to the chord formula numbers based on degrees of the major scale. E.g. the third scale degree of the major scale – the major third interval.

It’s easy, when first learning music theory to think these are the same, but it’s important to understand the difference between scale degrees and intervals, despite the fact that in some instances e.g. the major scale they will appear to be of the same value.

How intervals are named

Intervals are named by their interval type and their interval number e.g.

  • Unison
  • Seconds
  • Thirds
  • Fourths
  • Fifths
  • Sixths
  • Sevenths
  • Octaves

Perfect intervals (P)

Intervals that are either unison, 4th, 5th or a whole octave are known as perfect intervals. They remain the same whether inverted. An inverted interval is an interval that has been turned upside down e.g. the starting note becomes the final note and vice versa.

Non perfect intervals

Non-perfect intervals are either major or minor intervals and include the second, third, sixth and seventh.

Augmented intervals (A)

Augmented intervals are intervals that have been raised by half a step.

Diminished intervals (d)

Diminished intervals are intervals that have been lowered by half a step.

How major chords are built using intervals

As already discussed, major chords consist of the root note or first, the 3rd (the 3rd is major unless otherwise indicated) and the 5th (perfect fifth) intervals.

If we build a A major chord, starting on the A (the root note) we get the following notes:

‘A’ Chromatic Scale
A  –  A♯ –  B – C – C♯ – D – D♯ – E – F – F♯ – G – G♯
  • The first note is the A.
  • A major third from the root note (4 half steps) is the C♯
  • The perfect fifth from the root (7 half steps) is the E

This means A major chord consists of A, C♯ and E

Qualities and Intervals

Below is a list showing the common chord qualities and their respective intervals.

Quality Interval Formula
Major Root – Major third (M3) – Perfect Fifth (P5)
Minor Root – minor third (m3) – Perfect Fifth (P5)
Diminished Root – minor third (m3) – Diminished fifth (dim5)
Augmented Root – Major third (M3) – Augmented Fifth (Aug5)

Summary

While there is a great deal more that could be expanded upon with regard to chords, the intention of this article is to provide an introduction to chord theory in a way that is simple for those new to guitar and music theory in general. By learning the basics and understanding how chords are constructed you are building a foundation that can be built upon as your knowledge of music theory increases.

I highly recommend if you found this article useful to also check out our articles on learning all notes on the guitar fretboard along with our introduction to music scales as each will help strengthen your knowledge and help you become not only a more knowledgeable guitarist but also a better musician in general. As always if you have a question please be sure to leave a comment below.

Marty


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