Chord Scales Explained: How to Find Chord-Scale Relationships

In music theory, a chord is a group of two or more notes occupying the same time duration in a piece of music. These notes do not have to be played simultaneously, and they don’t all have to be played by the same instrument. As such, a chord could be played by a single musician strumming the six strings of her guitar, or a chord could be played by an orchestra featuring fifty individual players playing one note each.

Most chords contain three pitches (triads) or four pitches (typically sixth chords or seventh chords), but some styles of music—most notably, jazz—favor chords with five pitches, six pitches, or more. Different types of chords have different sonic characteristics. Major chords (characterized by the major third scale degree) often sound cheerful while minor chords (characterized by the minor third scale degree) sometimes sound somber. Dominant chords (characterized by a major third and a flat seventh scale degree) tend to sound unresolved.

In Western music, scales are divided into twelve equal increments. Notes twelve increments apart from each other are said to be an octave apart. For instance, the note G5 is an octave above the note G4, and there are eleven equally spaced notes in between them. Moving from one of these twelve notes to the next is a half step. Moving up or down in two-note increments is moving in whole steps.

To create most Western musical scales, pick seven of the twelve possible notes, which are spaced apart in half-step and whole-step increments. That specific pattern of seven notes is what gives a scale its unique sound.

The fundamental scale of Western music is the major scale, and it consists of seven notes. Starting from the lowest note, and going up, the notes of this diatonic scale are:

1 - the “root” of the scale
2 - a whole step up from the root
3 - a whole step up from the 2nd
4 - a half step up from the 3rd
5 - a whole step up from the 4th
6 - a whole step up from the 5th
7 - a whole step up from the 6th

Then, with one more half step, arrive back to the “root”—only now an octave higher than before.

A natural minor scale is similar to a major scale, but with a few half steps where there were previously whole steps.

1 - the “root” of the scale
2 - a whole step up from the root
3 - a half step up from the 2nd
4 - a whole step up from the 3rd
5 - a whole step up from the 4th
6 - a half step up from the 5th
7 - a whole step up from the 6th

And then one final whole step to get back to the root—but again it’s an octave higher than before.

The chord-scale system of music theory uses the notes in a musical scale to create a series of chords. For example, you can use the pitches of a C major scale (C, D, E, F, G, A, B) to create a full scale of diatonic chords.

• First scale degree, C major: C is the tonic of a C major scale, and it is the root note of our first chord. A C major chord is built with the notes C-E-G, and these are all notes from the C major scale.
• Second scale degree, D minor: D is the second degree of the C major scale, and we can build a D minor triad using three pitches from the scale: D-F-A.
• Third scale degree, E minor: The chord tones of E minor are E-G-B. These are all chord tones in C major.
• Fourth scale degree, F major: The F major triad features the notes F-A-C. All of these are scale tones in C major.
• Fifth scale degree, G major: The G major triad is built G-B-D. Once again, these are all notes from the C major scale.
• Sixth scale degree, A minor: We can spell an A minor chord with the notes A-C-E, which all come from the C major scale.
• Seventh scale degree, B diminished: Our final degree of this C major chord scale is B diminished, which is spelled B-D-F.

These are the seven diatonic chords formed by a C major scale, but the chord-scale system can apply to any type of scale, including natural minor, harmonic minor, and melodic minor keys. You can apply the system to pentatonic scales, which only have five notes. The system even works for building chords off of the notes of a musical mode.

A mode is simply a scale pattern that can begin on any note in the scale, not just the root. Modes are variations on scales, which are one of the fundamental elements of tonal music. There are seven types of modes, each of which begins on a different scale degree.

It is useful to know the major modes, how they are constructed, and what they sound like.

1. 1. Ionian mode: The Ionian mode is a major scale pattern starting on the root. A C major scale and the C Ionian mode have the same exact set of notes: C-D-E-F-G-A-B. This means that “Ionian mode” is another way of saying “major scale.”
2. 2. Dorian mode: The Dorian mode is a major scale pattern starting on the second degree. The Dorian mode is a cousin to the minor scale and is quite popular with guitarists from jazz greats like Pat Martino to shredders like Kirk Hammett.
3. 3. Phrygian mode: The Phrygian mode is a major scale pattern starting on the third degree. The Phrygian mode also has a minor tonality and tends to evoke the Arabian music of Spain and North Africa.
4. 4. Lydian mode: The Lydian mode is a major scale pattern starting on the fourth degree. The Lydian mode is closely related to a major scale and tends to evoke a “lifting” sensation. It’s popular in inspirational film music like John Williams’ score for ET: The Extra-Terrestrial.
5. 5. Mixolydian mode: The Mixolydian mode is a major scale pattern starting on the fifth degree. Also closely related to a major scale, the Mixolydian mode is heard all over rock, blues, and fusion. Listen to the guitar solos in Steely Dan’s “Reelin’ In The Years” for some classic Mixolydian playing.
6. 6. Aeolian mode: The Aeolian mode is a major scale pattern starting on the sixth degree. This is actually the same exact note pattern as a minor scale, so like the Ionian mode, saying “Aeolian mode” is another way of saying “minor.”
7. 7. Locrian mode: The Locrian mode is a major scale pattern starting on the seventh degree. The Locrian mode is dense and thorny and rarely used. Sometimes jazz soloists use it over diminished chords, but it doesn’t sound pleasing in long passages.

Musicians can build triads starting on every note of a major scale. Notate these chords using Roman numerals with capital letters for major chords and lowercase letters for minor and diminished chords. The chord scale theory system works as follows:

• I: A major triad starting on the first degree of the scale.
• ii: A minor triad starting on the second degree of the scale.
• iii: A minor triad starting on the third degree of the scale.
• IV: A major triad starting on the fourth degree of the scale.
• V: A major triad starting on the fifth degree of the scale.
• vi: A minor triad starting on the sixth degree of the scale.
• viiº: A diminished triad starting on the seventh degree of the scale.

When you assign these Roman numerals to specific keys, you get a specific set of chords. For instance, take B♭major. The chords associated with that scale are:

• B♭major (the I)
• C minor (the ii)
• D minor (the iii)
• E♭major (the IV)
• F major (the V)
• G minor (the vi)
• A diminished (the viiº)

If you’re working in the natural minor scale, these are the chords built off each degree of that scale:

• i: A minor triad starting on the first degree of the scale.
• iiº: A diminished triad starting on the second degree of the scale.
• ♭III: A major triad starting on the third degree of the scale, which is sometimes called the flat third degree.
• iv: A minor triad starting on the fourth degree of the scale.
• V: A major triad starting on the fifth degree of the scale.
• ♭VI: A major triad starting on the sixth degree of the scale, which is sometimes called the flat sixth degree.
• ♭VII: A major triad starting on the seventh degree of the scale, which is sometimes called the flat seventh degree.

To see how this works, assign these Roman numerals to an actual minor key in the C natural minor scale. The chords associated with it are:

• C minor (the i)
• D diminished (the iiº)
• E♭ major (the♭III)
• F minor (the iv)
• G major (the V)
• A♭ major (the♭VI)
• B♭ major (the♭VII)

You can create diatonic chord progressions from any scale you can think of—even chromatic scales, which contain all twelve pitches used in Western music. Different keys and chord types will produce different sets of chords. To discover the different types of chords you can make from scale tones, remember the following tips.

1. 1. Most chords are built on triads. Triads contain a root note, a third (either a major third or a minor third), and a fifth (either a natural fifth, a diminished fifth, or an augmented fifth). Look for ways to build triads using the notes in a given scale.
2. 2. Each note in the scale is the root of some kind of chord. Focus on creating a full set of chords such that each note in the scale serves as the root of its own chords. If you are playing guitar chords, go straight up the fretboard along the low E string. Create barre chords using each note in the scale and decide whether these chords need to be major chords or minor chords based on the notes in the scale.
3. 3. You can change the voicings around. One advantage of chords is that the root note does not need to be the lowest note in the chord voicing. For example, you can play a B minor chord (B-D-F♯) in "root position," where B is the lowest note, or you can play it with D or F♯ as the lowest note. Experiment with the way these different voicings sound, and decide what you like best.

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