The Triad

A First Chord: The Triad

Chords are generally defined as a group of three or more pitches sounding simultaneously. The most common type of chord is the triad. Triads are three-note chords ("tri" means three). The three notes of the triad are labelled root, third, and fifth. The root is the primary note of the triad and is also where the chord gets its name. In other words, if the root of a triad is C, then the name of the chord is also C.

The next note is placed a third higher than the root, it is called the third, in this case that's the note E. Finally, the last note will be placed a fifth above the root and is called the fifth, in this case the note G.

Triad's are named in two parts, the first part is a letter name based on the root note of the chord, the second is its quality. Chord quality is very similar to interval quality in that you have four possible qualities for triads: major, minor, diminished, and augmented. But since triads have three notes, their quality is based on all the intervals the triad contains. For instance, a C triad contains the notes C-E-G, therefore its quality is based on the interval from C to E and the interval from C to G.

To fully name a triad, you need to write its letter name (its root note), then if the triad is not major, a symbol is added to identify it as minor, diminished, or augmented. If only the letter name of the triad is written, it is assumed to be major. Here is a quick table showing how a C triad will be labelled in each of its four possible qualities.

Root Note Quality Written:
C Major C
C Minor Cm
C Diminished Co
C Augmented C+

Finding Triad Quality with the Major Scale

One common way to find triad quality is to use the major scale. We can find any major triad by constructing a major scale on the triad's root note. For example, a C major triad can be derived from a C major scale. Let's build a C triad starting by building a C major scale. Then we need to focus on three specific scale degrees: 1, 3, and 5. Scale degree 1 will be the root, degree 3 will be the third, and degree 5 will be the fifth. This means that the notes C (root) , E (third), and G (fifth) make a C major triad. The notes required for any major triad can be found in this fashion:

  1. Find the corresponding major scale for the triad you want
  2. Identify the notes on scale degrees 1, 3, and 5

Let's try this a few more times with some examples. Find the solution yourself, then click the button to see the answer.

We can now take this one step further to find any of the other three triad qualities. We simply need to be able to compare the major triad to the other qualities: minor, diminished, and augmented. To create a minor triad from a major one, we simply lower the third by a half-step. For example, a C major triad is spelled C, E, G. The third of a C triad is E, to lower the note E by a half-step we need a flat. Therefore a C minor triad is spelled C, E-flat, G. A similar process is required for diminished. To create a diminished triad, we lower both the third and the fifth of the major triad by a half-step. By way of example, our same C major triad from above would then need both the E (third) and the G (fifth) to have a flat. C diminished is then spelled C, E-flat, G-flat. Lastly, to make any major triad augmented we raise the fifth by a half-step. So our C major triad would need the G to be raised, giving us a C augmented spelling of C, E, G-sharp.

Here is a table summarizing how to alter any major triad to find any of the other three triad qualities. We will use the A major triad from above (A, C-sharp, E) as our example.

Quality Desired Action (by half-step) Major Triad Spelling Result
Minor Lower the third A, C-sharp, E A, C, E
Diminished Lower the third and fifth A, C-sharp, E A, C, E-flat
Augmented Raise the fifth A, C-sharp, E A, C-sharp, E-sharp

Finding Triad Quality by Interval

As mentioned in the Naming Triads section, a triad's quality is based on the combination of two intervals. We can look at these intervals in two ways when solving triad quality:

  1. Intervals from the root note. Example: a triad with C for its root would contain a third from C to E and a fifth from C to G
  2. Stack of two thirds. Example: a triad with C for its root would contain a third from C to E and another third from E to G.

Which method you choose is not particularly important; they will both require you to solve two intervals per triad. You might make your choice depending on whether you feel like fifths are easy to solve, since one type contains a third and fifth, and the other only thirds. Once you choose your method, you will need to memorize which interval combination makes each of the four triad qualities: major, minor, diminished, augmented. We like to think of these as quality "recipes." Below are two tables, the first showing the interval recipe for intervals above the root, the second showing stacked thirds.

Triad Qualities using Intervals from the Root
Quality Intervals above the Root Example using C Triad
Major Major 3rd, Perfect Fifth C Major Triad
Minor (m) Minor 3rd, Perfect Fifth C Minor Triad
Diminished o Minor 3rd, Diminished Fifth C Diminished Triad
Augmented + Major 3rd, Augmented Fifth C Augmented Triad
Triad Qualities Using Stacked Thirds
Quality Stacked Thirds Example using C Triad
Major Major 3rd, Minor 3rd C Major Triad
Minor (m) Minor 3rd, Major 3rd C Minor Triad
Diminished o Minor 3rd, Minor 3rd C Diminished Triad
Augmented + Major 3rd, Major 3rd C Augmented Triad

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