What Does I6 4 Mean in Music Theory?


Martha Robinson

If you’re interested in music theory, you may have come across the term “I6 4” in your studies. This term refers to a specific chord that is commonly used in various musical genres. In this article, we’ll explore what I6 4 means and how it is used in music theory.

Understanding Chord Notation

Before we dive into I6 4 specifically, it’s important to understand some basics about chord notation. In music theory, chords are often written out using a shorthand notation that tells you what notes are included in the chord and how they are arranged.

For example, a C major chord is often written as “C,” while a C minor chord is written as “Cm.” The letter represents the root note of the chord, while any additional symbols indicate modifications to that basic chord.

What Does I6 4 Mean?

Now that we’ve covered some basics about chord notation, let’s take a closer look at I6 4 specifically. The “I” stands for the Roman numeral one, which indicates that this is a chord built on the first note of a major scale. So if we’re in the key of C major, for example, I would mean a C major chord.

The “6” and “4” refer to specific notes within that C major chord. In this case, the 6 refers to the note A (which is six scale degrees above the root note of C), while the 4 refers to the note G (which is four scale degrees above the root).

So when we put it all together, I6 4 refers to a specific type of C major chord that includes the notes C, E, G, and A.

Where Is I6 4 Used?

Now that we know what I6 4 means, let’s talk about where it is used in music theory. This chord is often used in what is known as a “cadential six-four” progression.

A cadential six-four progression is a specific type of chord progression that creates a sense of resolution or conclusion in a piece of music. It typically involves moving from a V chord (which is built on the fifth note of the scale) to a I chord (which, as we’ve already discussed, is built on the first note of the scale).

In this progression, the V chord often appears in what is known as “second inversion,” which means that the fifth note of the chord (the note that gives it its name) is played in the bass. So if we’re in C major, for example, the V chord would be G major, and in second inversion, it would include the notes D, G, and B.

The next step in this progression is to move to I6 4. This creates a specific sound that helps signal to listeners that a piece of music is coming to an end. The A note in I6 4 provides a sense of tension that resolves when we move back to C major (which includes the notes C, E, and G) for a final resolution.


In summary, I6 4 is a specific type of chord used in music theory to create tension and resolution within a piece of music. It’s often used as part of a cadential six-four progression that helps bring songs to an end. By understanding what this notation means and how it fits into larger musical structures, you can deepen your appreciation for the complexity and beauty of music theory.