Just as scale degrees are designated by Arabic numerals (1, 2, 3...), chords are
similarly designated by Roman numerals (I, II, III). For example, in the key of C
major the notes are C,D,E,F,G,A,B and we have designated them as
1,2,3,4,5,6,7. However, when we consider the triad chords in the key of C we
have Cmaj, Dm, Em, Fmaj, Gmaj, Am, Bdim. These are designated
I,II,III,IV,V,VI,VII. When speaking about these chords, for instance in the key of C
major, we would call Gmaj the
five chord
, Dm the
two chord,
Fmaj the
four chord
and so on.
There is no single agreed-upon system for numbering chords. One system uses
upper-case and lower-case Roman numerals to distinguish whether a chord is a
major or a minor (Dm = ii, Fmaj = IV). The Harmonizer uses upper-case Roman
numerals for all chords. However, if the chord happens to be minor, a lower-case
“m” will appear next to the Roman numeral (ex: VIm). In the case of diminished
chords such as the seven chord, the Roman numeral will be followed by a super-
script circle (ex: VII
O
). A four-note dominant chord will be written V7.
Major and Minor
In the Common Chord Substitution section of the Harmonizer the one chord (I) of
the major scale is found at the top of the column of chord roots. This chord is
derived from the major key as appearing in the key designator of the Major and
Natural Minor Scales section. Since the natural minor scale begins counting from
the sixth note of the major scale, the chord that has this note as its root is the
one chord (Im) of the minor scale relative to the major. Though they share the
same chords, they perform different harmonic functions.
C
D
E
F
G
A
B C
I
IIm
IIIm IV
V
VIm
VII[ I
Im
II[ <III
IVm
Vm <VI
<VII
Im
A
B
C
D
E
F
G
A
C
D E<
F
G A<
B<
C
Relative Minor
Parallel Minor
Major Scale
Chord Degree
A Minor
C Minor
C Major
{
1.
Chord Degrees
Common Chord Substitutions
This column indicates the root of the chord, its chord name, and the theoretical
name which describes the chord’s harmonic function. Each of the seven chord
degrees (I, II, III, etc.) performs a slightly different function in a piece of music.
Knowing a chord’s function is important when making chord substitutions.
The root note in the window combines with the suffixes to the right to spell out
the name of the chord which is to be replaced. The theoretical names as pre-
sented in this section apply only to the chords of the diatonic major scale.
Name and Function
Common Chord Substitutions
21
2.
