What are the capitalized roman numerals in a minor key [duplicate]

Question

I've heard that for major scales, the capital letters are always I, IV, and V. What are they for minor scales?

Answer 1

Every major scale have a relative minor starting on the 6th degree, vii.

In the major key the triads that occur on each scale tone are as follows.

I, Major, (1, 3, 5)

ii, minor, (2, 4, 6)

iii, minor, (3, 5, 7)

IV, Major, (4, 6, 8)

V, Major, (5, 7, 2)

vii, minor, (6, 8, 3)

vii, diminished, (7, 2, 4)

Where (1, 3, 5) for example refers to the notes of the key that are used to make the chord. As a minor chord its formula is still (1, b3, 5). You can check the intervals for correctness.

If you use the natural minor scale they are all the same since that scale has the exact same notes as the relative major scale. The only difference is that we would call the first note of the minor scale the "One", and denote it i. So the roman numerals would be i, ii, III, iv, v, VI, VII and have the character, minor, diminished, Major, minor, minor, Major, Major.

When we write music in minor keys we typically use the harmonic or melodic minor to get the leading tone. The melodic minor scale, for example, has a different form when ascending as compared to descending. The ascending scale is (1, 2, b3, 4, 5, 6, 7, 8) and descending it is the natural minor (8, b7, b6, 5, 4, b3, 2, 1).

To figure out which degrees are upper case or lower case roman numerals (major or minor) you write out the triads and see what chord you get.

For melodic minor you get the following.

i, minor, (1, b3, 5)

ii, minor, (2, 4, 6)

III, augmented, (b3, 5, 7)

IV, Major, (4, 6, 8)

V, Major, (5, 7, 2)

vi, diminished, (6, 8, b3)

vii, diminished, (7, 2, 4)

As compared to the chords of the natural minor scale the IV and V are both major in this case. And you have an augmented chord on the III, which is the I of the relative major key.