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INTRODUCTION
This set of lessons will help you understand how chords are named and show you how to construct a wide range of chord types, based on a set of simple formulae.

Triads (Major, minor, diminished & augmented)
Seventh chords
Extended chords (9th, 11th & 13th)
Added note, suspended, slash and power chords

Before you start:
To follow this method you should first know:
1. How to name any note on the guitar, by counting up from the nut, fret by fret if necessary.
2. What Tones and semitones (British system) or whole steps and half steps (American system) are. (A semitone or half step equals a distance of one fret. A tone or whole step equals two frets).
3. How to make any major scale. To make a major scale you start on any given note and go up in pitch by tones and semitones (or whole steps and half steps) in this strict order:
TTSTTTS (T = tone S = semitone)
or
WWHWWWH (W = whole step H = half step)
So a scale such as G major will be
G(T)A(T)B(S)C(T)D(T)E(T)F#(S)G
G(W)A(W)B(H)C(W)D(W)E(W)F#(H)G

Here are the ‘natural’ major scales for reference:
A major = ABC#DEF#G#A
B major = BC#D#EF#G#A#B
C major = CDEFGABC
D major = DEF#GABC#D
E major = EF#G#ABC#D#E
F major = FGABbCDEF
G major = GABCDEF#G

If you need a scale starting on a flat (b) or sharp(#) note, you can simply take the nearest natural scale and modify EVERY NOTE equally. For example to make Ab major from A major, flat every note. Natural notes will become flat and sharp notes will become natural, as follows:
A major = ABC#DEF#G#A
Ab major = AbBbCDbEbFGAb

DEFINITION OF A CHORD
Chords are notes sounded together. According to the most common definition, a chord has at least three differently named notes. The individual notes of the chord are called chord members, and the chord’s name tells us something about which notes the chord consists of.

The chord’s name
Chords are named in two main parts. The first part is a note name, and the second part contains information about the type of chord it is, and about the notes that it contains.

For example, the chord named A flat major seventh has two main parts to its name. The first part is the note name A flat (Ab) and the second part is major seventh (maj7)
Part 1 – Ab. This corresponds to the main note in the chord and is called the root of the chord. It’s the note that the chord has been built upon.
Part 2 – major seventh. This is the chord type. In combination with the root, this part tells us something about the notes required to produce this particular chord. The name itself is derived from degrees of the major scale.

The chord formula
Although the chord’s name gives some information about its make-up, we can find the exact notes by referring to a ‘formula’ associated with every chord type. This consists of numbers that correspond to the major scale. For example, the formula for a major chord is 1 3 5. That simply means that a chord such as C major will consist of the first, third and fifth notes of the C major scale. Every chord type has its formula, and you need to memorise the formula for each chord type. That’s not as difficult as it sounds, as the chord’s name will usually remind you what the formula is for any particular chord.

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The simplest type of chords are triads, which are composed of three notes. There are only four types of triad.
Two of them are extremely important and common and are the familiar major and minor chords.
The formulae for those chords are:

Major = 1 3 & 5
Minor = 1 b3 & 5

The major chord
Both are in relation to the major scale. But which major scale? The one that starts on the chord’s root. So if we want to know the notes of the chord C major, for example, we take notes 1, 3 & 5 of the C major scale. The notes of the C major scale are CDEFGAB and notes 1, 3 and 5 are C E & G.

That means that the chord of C major contains those three note names and no others. It can have duplicates, though. On a six string guitar, it can have maybe three Cs an E and a couple of Gs – or any other combination. A pianist can manage up to ten using every finger – but still must play only Cs Es and Gs. At the risk of labouring the point, a full symphony orchestra can have well over seventy notes in a C major chord – but every one, without exception, will either be a C an E or a G. As long as it has no notes other than those it is a C major chord. If you add any note other than C, E or G, it will no longer be a C major chord.

Here are some common C major shapes using the string/ frets notation with the equivalent notes contained in the chord. (X = unplayed string)
X 3 2 0 1 0 = CEGCE
0 3 2 0 1 0 = ECEGCE
3 3 2 0 1 0 = GCEGCE
X 3 2 0 1 3 = CEGCG
X 3 5 5 5 3 = CGCEG
8 10 10 9 8 8 = CGCEGC

The minor chord
The formula of the minor chord is 1 b3 5. Again we use the notes of the major scale. To find the notes of the chord, C minor, we use the C major scale. (CDEFGABC).

The first note is C, exactly as it was with the C major chord.
Next we want the note flat 3 (b3). C major's '3rd', as we saw, is E. To make it a flat third (b3) we simply keep the letter name but lower the note by a semitone (or half step) i,e., Eb, instead of E.
The next note is note 5 of the scale, which is G.
So the three notes of our C minor chord are C Eb & G. compared to the C major chord which are C E & G
Comparing them side by side we can see how they are closely related.
C major = 1 3 5 = C E G
C minor = 1 b3 5 = C Eb G

Here are the two most common C minor shapes
X 3 5 5 4 3 = C G C Eb G
8 10 10 8 8 8 - = C G C Eb G C

Other triads
Two other triads exist, though they occur much less frequently. They are the diminished and augmented chords and consist of the notes
Diminished = 1 b3 b5.
Built on the root note of C, we would have C Eb and Gb.
Augmented = 1 3 #5.
Similarly a C augmented chord is C E G#

Diminished chords are often represented by the symbol, °
Augmented chords are often represented by the symbol, +

Summary of triads
C major = 1 3 5 = C E G
C minor = 1 b3 5 = C Eb G
C diminished = 1 b3 b5 = C Eb Gb
C augmented = 1 3 #5 = C E G#

Triads: chords built from thirds.

If you're familiar with intervals, you can also think of triads as stacked thirds, i.e., intervals of thirds built on top of other thirds, as follows:
Major chord = Maj 3rd + minor 3rd
Minor chord = Minor 3rd + major 3rd
Augmented chord = Major 3rd + major 3rd
Diminished chord = Minor 3rd + minor 3rd.

PRACTICE SECTION
Follow this 3-step method to produce any major, minor, diminished or augmented chord.

Example
Make the chord G minor

Step 1 - The root of the chord is G, so we'll refer to the G major scale and then modify as necessary to make the chord minor.
(The G major scale is G A B C D E F#)

Step 2 - Apply the 'minor chord formula' to the G major scale
The formula for minor chords is 1 b3 5 which produces the notes G Bb D.

Step 3 Place the notes G Bb & D anywhere on the fretboard within reach of your fingers.

Remember, you only need those three notes (G Bb & D) in any order to produce a correct G minor chord. But on guitar, we normally want more than three notes for a fuller sound, especially if we want to strum it. So, we can double any of those notes, higher or lower.

Examples
XX5333 = X X G Bb D G
355333 = G D G Bb D G
355336 = G D G Bb D Bb
XX0333 = X X D Bb D G

Root position and inversions
Notice that in all of those examples apart from the last one, the lowest note is also the root note. This is the most common way to arrange chords, because when the root is the lowest note, the chord sounds more balanced. In that arrangement, the chord is said to be in 'root position'. If any note other than the root is the lowest note, then the chord is said to be inverted as in the last example. Inverted chords (or inversions) sound less balanced or solid, so are used much less often. Sometimes, though, you might actually want a little less solidity in the chord, perhaps for a more delicate sound, or you might want a certain bass note other than the root as part of a bass run, in which case you'd use an inversion, such as the last G minor example.
Sometimes in chord song sheets, you're required to play the chord inverted - this is often shown with a slash followed by the required bass note, such as Gm/D. It's still a G minor chord but the bass note has to be D.

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Seventh chords are the most important chords after the major and minor triads. They consist of the major or minor triad plus the seventh scale degree, which may be modified depending on the type of seventh chord required.

Types of seventh (with formula)

The dominant seventh (1 3 5 b7)
This chord is generally referred to simply as a seventh chord, e.g., C7. The name dominant comes from the dominant scale degree, i.e. the fifth degree (note) of major or minor scales. Originally ALL seventh chords were built on this scale degree. This is no longer the case as they now often appear built on any scale degree, but the name has stuck.
Example
G seventh (G7) = 1 3 5 b7 of the G major scale (GABCDEF#) = G B D F
Some common shapes are:
320001 = GBDGBF
353433 = GDFBDG
XX5767 = XXGDFB

The major seventh (1 3 5 7)
The word ‘major’ in this case is referring to the fact that the seventh scale degree is not a flat seven, as it is in the case of the dominant seventh, but simply the unmodified seventh note of the major scale
G major seventh (G maj7) = 1 3 5 7 of the G major scale (GABCDEF#) = G B D F#
Some common shapes are:
320002 = GBDGBF
XX5432 = XXGBDF#

The minor seventh (1 b3 5 b7)
For example, Am7 = 1 b3 5 b7 of the A major scale (ABC#DEF#G#) = A C E G (notes 3 & 7 have been flatted from sharp notes to natural notes)
Some common shapes are
X02010 = AEGCE
X02213 = XAEACG
575555 = AEGCEA

The minor major seventh (1 b3 5 7)
This chord is very rare and also very discordant.
For example, Amin maj7 = 1 b3 5 7 of the A major scale (ABC#DEF#G#) = A C E G#
Some typical shapes are:
X02110 = XAEG#CE
577595 = AEACG#A (the high A is often muted in this shape to avoid a semitone clash with G#)

The diminished seventh (1 b3 b5 bb7)
This is a very useful chord because it has some unusual properties. The bb7 note (double flatted seventh) sounds the same as the 6th note of the scale, but to be correctly named as a diminished seventh, the 7th degree of the major scale has to be double flatted.
For example E diminished 7th = 1 b3 b5 bb7 of the E major scale (EF#G#ABC#D#) = E G Bb Db
An unusual property of the diminished seventh chord is that the distance (interval) between each note is equal. The interval is a minor third. As all the intervals are identical, any one of them could be the root. Which means every diminished seventh shape can have four names
For example, a common diminished seventh shape such as XX1212 could be Eb (or D#) dim7, A dim7, C dim7 or Gb (or F#) dim7

This ambiguity of identity makes them ideal chords for changing into other keys.

Typical shapes (e.g., E dim7)
XX2323 = X X E Bb Db G
X7868X = X E Bb Db G X

The only other chord that exhibits this strange property is the augmented triad (1 3 #5) as it’s the only other chord with equal spacing between its notes. The interval separating them is a major third, rather than the minor third of the diminished seventh chord.

The half diminished seventh (1 b3 b5 b7)
This chord is less common than the fully diminished seventh
For example E half dim7 = 1 b3 b5 b7 of the E major scale (EF#G#ABC#D#) = E G Bb D.
Typical shapes are:
XX2333 = X X E Bb D G
X7878X = X X E Bb D G
Another name for this chord is minor seventh flat fifth (min7b5).

PRACTICE SECTION
Use the three step method shown in the triad lesson to practise building seventh chords as follows:
Example – make the chord E7

Step 1 – Write the notes of the E major scale, which would give you:
E F# G# A B C# D#.

Step 2 – Apply the formula for (dominant) seventh chords.
The formula is 1 3 5 b7 , which gives the notes E G# B D.

Step 3 - Find those notes anywhere on the fretboard within reach of your fingers, such as:

020100 = EBDG#BE
022130 = EBEG#DE

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We saw in the triad section that chords are made from scale notes separated by intervals of a third. (Thirds are intervals spanning three letter names).

For example, C major (1 3 5) = C E G. C to E is a third (three letter names) and E to G is a third.

The seventh chords extend the triads by a further third, e.g., C Maj 7 (1 3 5 7) = C E G B .

We can extend the series even further, but to do so, we'll have to extend the notes of the scale over two octaves, rather than just one.

For example, a two octave scale of C major gives us the notes:

C D E F G A B C D E F G A B C

We build chords by taking alternate scale notes (underlined) because alternate scale notes are placed a third apart. We can consider the two octave scale as a chain of thirds from which all extended chords are derived.

A third higher than B is D. D is note 2 of the scale, but in this context we call it 9 to show its place in the chain of thirds. It doesn’t mean we have to play it higher than the lower D. And the chord will be called a ninth chord of some sort.

Extending the ninth chord by another third gives us the note F. F is scale note 4 but we call it eleven to show its place in the 2-octave chain of thirds, and so the chord containing it will be a type of eleventh chord.

The next and final third brings us to the note A which is note 6 of the scale, but here it’s called thirteen, and the chord containing it will be a type of thirteenth chord.

The chain of thirds
Here is how chords are built from the chain of thirds (example C chords).

C D E F G A B C D E F G A B C

C E G = C major (1 3 5)
C E G B = C maj7 (1 3 5 7)
C E G B D = C maj 9 (1 3 5 7 9)
C E G B D F = C maj11 (1 3 5 7 9 11)
C E G B D F A = C maj13 (1 3 5 7 9 11 13)

And that's as far as it goes. The thirteenth is the final extension because we’ve now used EVERY scale note. If we add another third after A, it will simply take us back to where we started, i.e., C. That’s why you’ll never hear any chord name numbered higher than thirteenth.

The above chords are those that occur naturally from the C major scale but any of the chord members (apart from the root) can be modified by sharping or flatting the note. The chord's name always indicates when that has been done (e.g., C maj9 b5).

Now we can look at a range of the extended chord types in turn:

Ninth chords

Type: Ninth (dominant ninth)
Scale notes:1 3 5 b7 9
Example: C9 = C E G Bb D
Typical shape: X 3 2 3 3 3 = C E Bb D G
Comment: Standard ninth chords consist of a dominant seventh plus the ninth scale note.

Type: Major ninth
Scale notes: 1 3 5 7 9
Example: C maj 9 = C E G B D
Typical shape: X3243X = C E B D.
Comment: This is a major seventh chord plus the ninth major scale note. Note that the fifth is not included in this particular shape, which illustrates the fact that fifths (unless they're diminished or augmented) aren't so important in most chords.

Type: Minor ninth (1 b3 5 b7 9)
Scale notes: 1 b3 5 b7 9
Example: C min 9 = C Eb G Bb D
Typical shape: 8 10 8 8 8 10 = C G Bb Eb G D
Comment: This is a minor seventh chord plus the ninth major scale note

Type: Augmented ninth
Scale notes: C E G Bb D#
Example: C +9 = X C E Bb D# X
Typical shape: X 3 2 3 4 X (X C E Bb D#X)
Comment: This is a chromatically altered chord often used in jazz and occasionally in rock music.

Eleventh chords
Eleventh chords contain six different notes. That means it’s very difficult to play them on guitar including every note. So we usually omit notes when playing it. We can omit scale notes 5 or 9 or both. They won’t be missed and it will still be called an eleventh chord. Some musicians, especially in jazz, may choose to omit the root of any chord provided that the essential harmonic flavour of the chord isn't compromised by doing so.

Type: Eleventh (dominant eleventh)
Scale notes: 1 3 5 b7 9 11
Example: C11 = C E G Bb D F
Typical shape: 8 8 8 9 8 10 (C F Bb E G D)
Comment: Eleventh chords contain what’s known as an avoid note. That means there’s a clash between the third of the chord and the eleventh (which is really a fourth). Sometimes the eleventh note is sharped to avoid such a clash. e.g., C major #11 (1 3 5 b7 9 #11).
Another way to avoid the clash is to omit the third. For example, the chord X33333 (X C F Bb D G) may be named C11 even though it lacks a third (E). However, without a third, the chord is also called a seventh suspended fourth, or ninth suspended fourth if the ninth hasn't also been omitted. (suspended chords are dealt with later in the lesson.

Type: Major eleventh
Scale notes: 1 3 5 7 9 11
Example: C maj11 = C E G B D F
Typical shape: 8 8 9 9 8 10 = (C F B E G D)

Type: Minor eleventh
Scale notes: 1 b3 5 b7 9 11
Example: C m11 = C Eb G Bb D F
Typical shape: 8 8 8 8 8 10 = C F Bb Eb G D
Comment: Minor elevenths are easier to manage, as they don't have the clash that the major version has. E minor 11 is the easiest chord possible in standard tuning using all strings. It's the full open string chord: 000000 (E A D G B E).

Thirteenth chords
Extending by one more third brings us to the final stop in the chain of thirds. All seven scale note are now accounted for. Playing a full thirteenth chord actually means playing the whole seven notes of the major scale at the same time.
However, whereas full eleventh chords are difficult to play on guitar without omitting some notes, full thirteenth chords are impossible, as they contain seven different notes. Omitting notes is obviously essential on a 6 string guitar, and the 11th, 9th or 5th (or all three) are commonly left out of thirteenth chords. The root of the chord may also be omitted from thirteenth chords, if necessary, as the essential harmonic flavour of this chord is supplied by the 3rd, b7th and 6th in combination.

Type: Thirteenth (dominant thirteenth)
Scale notes: 1 3 5 b7 9 11 13
Example: C 13: C E G Bb D F A
Typical shape: X32335 (X C E Bb D A)
Comment: The 5th and 11th are omitted from this shape.

Type: Major thirteenth
Scale notes: 1 3 5 7 9 11 13
Example: C maj 13 = C E G B D F A
Typical shape: 8 8 9 9 10 8 (C F B E A C)
Comment: The 5th and 9th are omitted from this shape.

Type: Minor thirteenth
Scale notes: 1 b3 5 b7 9 11 13
Example: C min13: C Eb G Bb D F A
Typical shape: 8 10 8 8 10 8 (C G Bb Eb A C)
Comment: The 9th and 11th are omitted from this shape.

PRACTICE SECTION

Use the three-step method shown in previous sections to practise building extended chords as follows:
Example – Make the chord A min 13.

Step 1 – Write the notes of the A major scale, which would give you:
A B C# D E F# G#

Step 2 – Apply the formula for minor thirteenth chords.
The formula is 1 b3 5 b7 9 11 13, which gives the notes A C E G B D F#.

Step 3 - Omit some unessential notes and find the others anywhere on the fretboard within reach of your fingers, such as:
X 0 2 0 1 2 = X A E G C F# (omitting the 9th & 11th)
5 7 5 5 7 5 = A E G C F# A (omitting the 9th & 11th)

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Added note chords
Added note chords are similar to extended chords except that they lack the 7th (chord member). We saw earlier how it was possible to omit certain notes from extended chords. such as the 11th, 9th and 5th - but never the 7th. Omitting the 7th converts it from an extended chord to an added note chord.
For example,
G 9 = G B D F A:
G add 9 = G B D A (also known as G add 2)

Types of added note chords
Type: Sixth
Scale notes: 1 3 5 6
Example: C6 = C E G A
Typical shape: 8 7 5 5 5 5 ( C E G C E A)
Comment: This is one of the few chords from which (if we have to omit any note) the 5th isn't normally omitted. Omitting the 5th (G) from the chord C6 would leave the notes C E A, which is just another spelling of A minor (A C E). The full C6 chord happens to have exactly the same notes as A minor 7 (A C E G). Those two chords share the same sound and shapes. The musical context usually determines which is the more correct name in any situation.
(If the 7th chord member is present, sixth chords become the extended chord type, thirteenth)

Type: Minor sixth
Scale notes: 1 b3 5 6
Example: C min 6 = C Eb G A
Typical shape: 8 10 10 8 10 8 (C G C Eb A C)

Type: Sixth added ninth
Scale notes: 1 3 5 6 9
Example: C6/9 = C E G A D
Typical shape: X 3 2 2 3 3 (C E A D G)

Type: Minor sixth added ninth
Scale notes: 1 b3 5 6 9
Example: C min 6/9 = C Eb G A D
Typical shape: X 3 1 2 3 X
Comment: The fifth is omitted from this shape

Type: Added ninth
Scale notes: 1 3 5 9
Example: C add 9 = C E G D
Typical shape: X 3 2 0 3 0 (C E G D E)

Type: Minor added ninth
Scale notes: 1 b3 5 9
Example: C min add 9 = C Eb G D
Typical shape: 8 10 10 8 8 10

Type Added eleventh
Scale notes: 1 3 5 11
Example: C add 11 = C E G F
Typical shape: X 3 2 0 1 1 (X C E G C F)

Type: Minor added eleventh
Scale notes: 1 b3 5 11
Example: C min add11 = C Eb G F
Typical shape: X X 10 10 8 11 (X X C F G Eb)

Suspended Chords
Suspended chords in modern usage, are special chords in which the 3rd of a major or minor chord has been displaced by either of its neighbours the 2nd or the 4th. The effect is one of 'suspension' and anticipation of the missing (usually major) 3rd making an appearance. Most of the time, that is still the case - a sus chord is almost always followed (resolved) by the major or (less often) the minor chord built on the same root. In jazz however, sus chords are often not resolved.

Type: Suspended fourth
Scale notes: 1 4 5
Example: C sus4 = C F G
Typical shape: X 3 5 5 6 3 (X C G C F G)

Type: Suspended second
Scale notes: 1 2 5
Example: C sus2 = C D G
Typical shape: X 3 5 5 3 3 (X C G C D G)

Type: Seventh suspended fourth
Scale notes: 1 4 5 b7
Example: C7sus 4 = C F G Bb
Typical shape: X 3 5 3 6 3 (X C G Bb F G)

Comment: Some sources maintain that Sus 2 chords are not genuine chords but simply sus 4 chords spelled differently. For example the chord F sus 2 (F G C) contains the same notes as C sus 4 (C F G).

Slash chords
Slash chords are chords in which a bass note is specified following a slash. For example the chord, G/F. means "play the chord G major and add the note F in the bass". Slash chords are found in sequences in which a moving bass line is required, such as the sequence:
C --- C/B --- Am --- Am/G
They can also be found in sequences in which a repeating static bass note (pedal point) is required under a changing chord progression, e.g.:
Am --- F/A --- D/A

Power chords
A Power chord is the name given to the interval of a perfect fifth (or perfect fourth), especially when played on electric guitars with overdriven amplification.
During the 1950s, the ever-increasing levels of amplication and overdrive were found to have an adverse effect on the sound of chords. Unlike single notes, chords sounded unclear at high distortion levels. Even simple major and minor chords could sound harsh and discordant. The solution was to omit the 3rd from major and minor chords leaving the two-note interval consisting of the scale notes 1 - 5. As this interval (a perfect fifth) is very pure and consonant, it sounds good even at high levels of power and distortion. These 'power chords' as they became known, are now used extensively throughout rock music. Although they consist of two different notes, either (or both) of those notes may be doubled an octave higher (or lower) as shown in the examples below:

Type: Power chord (fifth chord)
Scale notes 1, 5
Example: C5 = C G
Typical shape X 3 5 5 X X (X C G C X X)

Type: Power chord (fourth chord)
Scale notes: 1, 4
Example C4 = C F
Typical shape: X 3 3 5 X X (X C F C X X )

Inverted power chords.
If a 'fifth' power chord, such as C5 is inverted, it becomes identical to a 'fourth' power chord built on a different root.

For example:
C5 contains the notes of the perfect fifth interval C G. If we invert it, its notes are G C.
G4 contains the notes of the perfect fourth interval G C. If we invert it it becomes C G.
Technically, both names (C5 or G4) are correct, but calling it C5 is far more common.