I'm having trouble understanding the concept of "Triads" in music theory. I wanted to know everything about triads. I kinda understood C major triad but I'm having a lot of trouble with the D minor triad, so if it's possible please explain that as well. I would also love to learn about he Roman numbers that define major and minor and diminished triads. Any help is appreciated.


2 Answers 2


A triad is a collection of three notes that are stacked in consecutive thirds. In other words, the first measure of the example below is a triad, while the second one is not (because the F--G interval can never be a third). Note, however, that the third one is a triad, because it can be "reduced" to what you see in the fourth measure.

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There are three parts to a triad:

  • The root, which is the lowest pitch when you stack the triad in thirds. In the above example, C is the root of the triad in the first measure.
  • The third, which is the third above the root (E in measure one).
  • The fifth, which is the fifth above the root (G in measure one).

I recommend conceptualizing major triads in one of two ways:

  • Given a root, place a major third and a perfect fifth above it.
  • Given a root, place the third and fifth scale degrees of that major scale above it.

If you're unfamiliar with intervals, I say go with the latter option: think of the major scale associated with the root and then use the third and fifth members of that scale (we call these "scale degrees").

You can do the same thing with minor; just use scale degrees one, three, and five of the minor scale (any one will do) to create your triad. The last measure of the above example is the A minor triad; it uses scale degrees one, three, and five of A minor. (Note that while the third of the major triad is a major third above the root, the third of the minor triad is a minor third above the root.)

Now, beware! Some people claim that counting half steps is a good idea, and to create a major triad you just count 4 and then 7 half steps. Please do not do this. You will make errors, errors, errors, and more errors. Everyone messes up when they go this route.

So, for your D minor triad, just think through your favorite D minor scale. Let's say D natural minor: D E F G A Bf C D. Now, just pick scale degrees 1, 3, and 5: D F A is your D minor triad!

As for the Roman numerals, there are some patterns. The "diatonic triads" (triads built on scale degrees with no chromaticism, except for maybe the leading tone in minor) will follow this pattern in major and minor scales. Note that uppercase Roman numerals indicate major, while lowercase indicates minor. The lowercase with a circle indicates diminished.

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A triad is three notes played together. Usually they are a note apart from each other, as in 1-3-5, 2-4-6, 3-5-7 etc.

In the diatonic scale notes,1-3-5 is the major chord, and 2-4-6 will be the next chord, based on note no. 2, thus a minor chord. In key C, The 1-3-5 will consist of C-E-G which is C major. 2-4-6 will be D minor, the second chord in the key., 3-5-7 will be Emin., the third in the key, and so on.

As far as the Roman Numerals are concerned, I (in C) is C maj., ii is Dm, iii is Em, IV is F, V is G, vi is Am and vii is Bo. This works for all keys, so in, say, Eb, Eb = I, and Fm = ii etc.

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