Scale chord

Purpose

Given a major scale or minor scale in any key, it is possible to work out a set of triad (3 note) or 7th (4 note) chords that harmonize with that scale.

These chords sound good played underneath the notes of a given scale because they are made up only from notes in that scale.

In fact, for each note of the scale there is a corresponding triad and seventh chord that whose root ie. starting note, is that scale note.

Example

As an example, let's use the Eb major scale shown below.

Chords based on 1st scale note - the tonic

Triad chords are built using the 1st, 3rd and 5th notes of a scale so the first triad is constructed using notes Eb, G and Bb.

Seventh chords are built from triads, with one extra note - the 7th scale note.

So the 7th chord has notes Eb, G Bb, and D - scale notes 1, 3, 5, and 7.

Chords based on 2nd scale note

The 2nd chord's root - ie starting note, is the 2nd scale note - F, together with the 4th and 6th notes - Ab and C. ie. you count the 3rd and 5th relative to the chord root.

The 7th chord has the same notes, plus one extra note - the 8th scale note, which is the same note as the original tonic of the scale.

So the 7th chord has notes F, Ab, C, and Eb - scale notes 2, 4, 6, and 8.

Chords based on 3rd+ scale note

This process is repeated for the remaining chords - just move up the next scale note, make it the root, and calculate the 3rd, 5th and 7th scale notes above it.

Although at this point it appears that we have hit the the 'end' of the scale (note 8), the scale just repeats itself, so note 9 is the same as note 2 - note F, and so on.

So the 3rd chord's root is G, and the remaining triad notes are a 3rd above that - Bb, and D.

The 7th chord based on the 3rd note therefore has the above note plus note F - scale notes 3, 5, 7, 9 (2).

Chord Qualities

That was quite easy - all we did was skip each note of the scale to identify the next chord note.

The tricker bit is to work out the name of the chord we have created in each case.

Based on the notes we have in each chord, should the chord quality be major, minor, augmented, diminished, or something else ?

That depends (on a chord by chord basis) on the Note interval relationship between the root and the other chord notes.

More on these interval relationships are at Triad chord and Seventh chord, and the links at the top of this page describe, for a given key, these chords in detail - the notes to use, and the chord quality name.

The remainder of the text below is a summary of all of that information laid out in a couple of tables - first for triads, then for seventh chords.

Scales - triad chord qualities table

The chart below shows the triad chord qualities of the Triad chord for each of the 7 notes in the scale.

Table rows

The Note no. row is the note number of the scale which we want to be the root (or starting note) of the triad chord.

The Scale degree row is a name given to that note number that represents its purpose in the scale.

The remaining rows show the triad chord quality names for each of the scales.

For example, for the bold table cell shown below, we are saying that the name of the triad chord name for the 3rd scale degree (mediant) of the harmonic minor scale is always an augmented triad chord.

Using E-flat as the example key again, we know that the 3rd note of the Eb harmonic minor scale is note Gb. So the name of the triad chord we want is Gb augmented chord.

These chart rules always hold no matter which key the scale is in.

Symbols used

To understand the chord symbols ( ^{o +} ) used in this table have a look at Triad chord.

The roman numerals (i, ii, ii, iv, v, vi, vii) are used to identify the 7 chords in a scale. For example, it is common to see something like chord IV of the major scale meaning the 4th chord of the major scale.

The roman numeral will be in upper case if the chord is a major chord ie. has a major 3rd interval, and in lower case if the chord is minor chord ie. has a minor 3rd interval.

Scales - 7th chord qualities table

Below is a similar chart for 7th chords - exactly the same rules apply as for triad chords, except that the chord qualities are taken from the Seventh chord chart instead.

To understand the chord symbols ( ^{o + ø} ) used in this table have a look at Seventh chord.

The use of roman numerals for 7th chords works in the same way as triads described above - upper case for major 3rd chords, lower case for minor 3rd chords. The ⁷ is shown after each chord name to indicate it is a 7th chord.