Music Chords

Intervals and Stacking Thirds

In this session, we will be looking at a general overview of different music chords and the intervals used to make up these chords.

Chords are made up of 2 or more notes played simultaneously.

A power chord is a form of 2-note chord, consisting of the root note and a perfect 5th. The chord formula for a power chord is 1 - 5 (1st & 5th)

The most common chords are triads which are 3-note chords that are usually major, minor, suspended, augmented and diminished chords. These chords can be extended by adding notes forming seventh, ninth, eleventh and thirteenth chords.

Chords are generally classed by their root note; so for example, a C chord is built upwards from the keynote of C.

Music Notes & Chords

Music Chords have collective names, depending on the number of notes in the chord:

Dyad - 2 note chord
Triad - 3 note chord (most common)
Tetrad - 4 note chord
Pentad - 5 note chord
Hexad - 6 note chord

Stacking Thirds

Most chords are built by stacking thirds—either major thirds or minor thirds.

A major third is equal to 4 half steps or 4 semitones ( 2 tones)
A minor third is equal to 3 half steps or 3 semitones (1+1/2 tones)

Let us look at the 4 common triads: Major, Minor, Diminished and Augmented triads. (We will illustrate using the scale of C Major) We will also use a chromatic scale which means we play all the notes in half steps or semitones which is the shortest distance between notes.

1. Major Triad = Major third + Minor third:

C - C# - D - D# - E - F - F# - G

Take C and count 4 half-steps upwards and reach E.
Take E and count 3 half steps upwards and reach G... You have a C Major Triad (C)
From C - G is a Perfect 5th or 7 half-steps

2. Minor Triad = Minor third + Major third:

C - D♭ - D - E♭ - E - F - G♭- G

Take C and count 3 half-steps upwards and reach E♭
Take E♭ and count 4 half steps upwards and reach G... You have a C Minor Triad (Cm)
From C - G is a Perfect 5th or 7 half-steps

3. Diminished Triad = Minor third + Minor third:

C - D♭ - D - E♭ - E - F - G♭

Take C and count 3 half-steps upwards and reach E♭.
Take E♭ and count 3 half steps upwards and reach G♭... You have a C Diminished Triad (Cdim)
From C - G♭ is a Diminished 5th or 6 half-steps

4. Augmented Triad = Major third + Major third:

C - C# - D - D# - E - F - F# - G - G#

Take C and count 4 half-steps upwards and reach E
Take E and count 4 half steps upwards and reach G#... You have a C Augmented Triad (C aug)
From C - G# is an Augmented 5th or 8 half-steps

Stacking More Thirds

If you keep stacking major and minor thirds on top of a triad, you get a 7th chord.
Stack another third, and it becomes a 9th chord.
Add another, and you get an 11th chord.
Add one more, and you reach a 13th chord.
That’s a whole lot of stacking! 🥳

Understanding how chords are built by stacking thirds is essential when working with intervals. Once you grasp how triads are formed using major and minor thirds, you’re already well on your way to understanding the intervals used in more complex chords. C'mon, you're doing great! 💪

In popular music, a music chord is composed of several parts:

The root note
The foundational pitch on which the chord is built.
Example: C
The chord quality (type)
Describes the structure created by the 3rd and 5th.
Examples: major, minor, suspended, augmented, diminished
The Interval Numbers
Indicate which scale degrees above the root are included.
Examples: 3rd, 5th, 7th
Altered intervals
Specific scale degrees modified with accidentals.
Examples: ♭3, ♯5, ♭7
Added tones
Adds an extra note without forming a full extended chord.
Examples: Dadd4, Cadd9, C⁄9

Commonly used Triads:

Triads are three-note chords made up of the 1st, 3rd, and 5th notes of a scale. The four basic types of triads are major, minor, diminished, and augmented.

The following chart is based on the C Major Scale:
C - D - E - F - G - A - B

Chord Type	3rd Interval	5th Interval	Chord	Notes
Major Triad (C)	Major 3rd	Perfect	C, CM, CΔ, Cma, Cmaj	C – E – G
Minor Triad (Cm)	Minor 3rd	Perfect	Cm, C-, Cmi, Cmin	C – E♭ – G
Augmented Triad (C+)	Major 3rd	Augmented	C+, Caug	C – E – G♯
Diminished Triad (Cº)	Minor 3rd	Diminished	Cº, Cm(♭5), Cdim	C – E♭ – G♭

Commonly used 7th Chords:

Seventh chords, or tetrads, are four-note chords that include the 1st, 3rd, 5th, and 7th notes of a scale. They are formed by adding a fourth note to a triad (a three-note chord). This additional note is a third above the fifth of the triad, creating an interval of a seventh above the root of the chord.

The following chart is based on the C Major Scale:
C - D - E - F - G - A - B

Chord Type	3rd Interval	5th Interval	7th Interval	Chord	Notes
Dominant 7th	Major 3rd	Perfect	Minor	C7, Cdom7	C – E – G – B♭
Minor 7th	Minor 3rd	Perfect	Minor	Cm7, Cmin7, C–7	C – E♭ – G – B♭
Major 7th	Major 3rd	Perfect	Major	Cmaj7, CM7, CΔ7	C – E – G – B
Minor major 7th	Minor 3rd	Perfect	Major	Cm(Δ7), C–Δ7	C – E♭ – G – B
Augmented 7th	Major 3rd	Augmented	Minor	C+7, Caug7, C7+, C7+5	C – E – G♯ – B♭
Augmented major 7th	Major 3rd	Augmented	Major	C+Δ7, CM7+5, CM7♯5	C – E – G♯ – B
Diminished 7th	Minor 3rd	Diminished	Diminished	Cº7, Cdim7	C – E♭ – G♭ – B𝄫
Half-diminished 7th	Minor 3rd	Diminished	Minor	Cø7, Cm7♭5, C–7(♭5)	C – E♭ – G♭ – B♭

Extended Chords - 9th, 11th & 13th chords

Extended chords build on triads (three-note chords) by adding additional notes beyond the 7th. These extensions include 9th, 11th, and 13th chords. Notes added beyond the 13th typically repeat notes that are already present in the chord.The following will help to explain this.

A 9th is like a suspended 2nd (sus2) but the 2nd is played an octave higher.
C - D - E - F - G - A - B♭ - C - D
An 11th is like a suspended 4th (sus4) but the 4th is played an octave higher.
C - D - E - F - G - A - B♭ - C - D - E - F
A 13th is like a 6th but the 6th is played an octave higher.
C - D - E - F - G - A - B♭ - C - D - E - F - G - A

A 3rd above the last A on the 13th chord (A - B - C) will take you back to C (the root or tonic)... we start all over again so there is no point in going any further with 15th's, 17th's etc.

In summary, triads, 7th's, 9th's, 11th's, and 13th's take care of every note in a given music scale.

The following chart is based on the C Major Scale:
C - D - E - F - G - A - B

Chord Type	3rd, 5th, 7th Interval	9th	11th Interval	13th	Chord	Notes
Dominant 9th	dominant 7th chord	Major	–	–	C9	C – E – G – B♭ – D
Dominant 11th	dominant 7th chord	Major	Perfect	–	C11	C – E – G – B♭ – D – F
Dominant 13th	dominant 7th chord	Major	Perfect	Major	C13	C – E – G – B♭ – D – F – A

Notice that 9th, 11th and 13th chords are built on dominant 7th chords where the 7th degree of the scale is flattened. Also notice that,

a 9th chord can be written as C7add9 or C7/9 (notes are C - E - G - B♭- D)
not Cadd9 or C/9... where the notes are C - E - G - D
an 11th chord can be written as C9 add11 or C9/11 (notes are C - E - G - B♭- D - F)
a 13th chord can be written as C11 add13 or C11/13 (notes are C - E - G - B♭- D - F - A)

Suspended Chords

A sus chord or suspended chord is a 3 note chord or triad where the 3rd is omitted. This is replaced with a major 2nd or a perfect 4th. It is a music chord having a root, a major 2nd or perfect fourth (no third), and a perfect fifth. This results in two main chord types:

the suspended second (sus2) - a Major 2nd is 2 half-steps or semitones upwards from the root or tonic
the suspended fourth (sus4) - a Perfect Fourth is 5 half-steps or semitones upwards from the root or tonic

For example:
Csus2 consists of the notes C–D–G
Csus4 consists of the notes C–F–G

Take Note

When counting upwards from a note, don't include the first note, e.g., a major 3rd is 4 half- steps upwards from the tonic or root:
A major 3rd (four half-steps) from C is E:
C - C# - D - D# - E.
We count upwards from C, not counting C
When we talk about intervals or notes in a scale or chord, we refer to them as the 3rd, 5th, 7th notes etc. In these cases, we include the tonic or root note when counting.
The 5th note of a C Major scale or chord is G:
C – D – E – F – G (C or first note is included in the count).

In closing...

Wow, what a session. Don't worry too much if this doesn't make a lot of sense. Just take a deep breath and revisit Music Scales and Music Intervals. Here you can review any areas that might be causing you some difficulty.

Back to Music Chords Theory Back To Top