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 in succession.

C chord

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 build upwards from the keynote of C.

Music Notes & Chords

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

The majority of music chords are made up of thirds stacked on top of each other. They are 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

If you continue to stack major and minor thirds on a triad you end up with 7th's. If you stack them on 7th's, you get 9th's; stack them on 9th's, you get 11th's; stack them on 11th's you get 13th's... that's a lot of stacking!

It is important to understand the concept of stacking thirds when working with intervals. If you understand the stacking of thirds in forming triads, you are well on your way to understanding intervals in more complex music chords. C'mon, you're doing great!

piano line

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

1. The root note (e.g., C)

2. The chord type (e.g., major, minor, suspended, augmented , diminished)

3. The number of an interval (e.g., 3rd, 5th, 7th)

4. The altered interval (e.g., ♭3, #5, ♭7)

5. An additional interval number (e.g., Dadd4, Cadd9, C/9 )

Commonly used Triads:

Triads are 3 note chords consisting of the 1st, 3rd and 5th notes of a major scale.

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 are 4 note chords (pentads) consisting of the 1st, 3rd, 5th and 7th notes of a major scale. These music chords are formed by adding a fourth note to a triad (3 note chord), at an interval of a 3rd above the 5th of the chord. This creates the 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, C7, Cdom 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(M7), C−M7 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+(M7), CM7+5, CM7♯5 C - E - G# - B
Diminished 7th Minor 3rd Diminished Diminished Cº7, Cdim7 C - E♭- G♭- B♭♭
Diminished half-7th Minor 3rd Diminished Minor Cø7, Cm7♭5, C−7(♭5) C - E♭- G♭- B♭

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

Extended chords are 3-note chords or triads with extended notes beyond the 7th resulting in 9th, 11th, and 13th chords. Any notes added in 3rds after the 13th will simply copy notes already in the chord. The following will help to explain this.

  • A 9th is like a suspended 2nd (sus2) but the 2nd is played 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, 12th 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, the chord Csus2 consists of the notes C - D - G, while Csus4 consists of the notes C F G, respectively.

Take Note...
  • When you are 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, so 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, therefore 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. I have only given a general overview of music chords, but certainly enough to give you a basic understanding of what chords are made up of.
Back to Music Chords Theory

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