If you’re interested in music theory, you may have come across the term “I64”. So, what exactly is I64 in music theory?

Understanding Chord Inversions

To understand I64, we need to first understand chord inversions. In music theory, a chord is a set of three or more notes played together.

Chords can be played in different ways by changing the order of the notes. This is called inversion.

Inversion changes the position of the root note of a chord. The root note is the note that gives a chord its name and is usually the lowest note in the chord. When we change this note’s position, we create different voicings and sounds.

The Roman Numeral System

The Roman numeral system is used to analyze and describe chords in music theory. It assigns a roman numeral to each chord based on its relationship to a key center.

For example, in the key of C major, the I chord would be C major (C-E-G), the IV chord would be F major (F-A-C), and so on. The Roman numeral system allows us to easily analyze and understand chords within their musical context.

I64 Chord Inversion

Now that we understand chord inversions and the Roman numeral system let’s talk about I64.

I64 refers to a specific type of inversion for a chord built on scale degree 4 (IV) in a major key. It means that the third of the IV chord becomes the lowest note or bass note, while keeping all other notes above it in their original positions.

For example, in C major key, IV would be F major (F-A-C). If we apply I64 inversion to this chord, it becomes A-C-F with A being the lowest or bass note.

Uses Of I64 Chord Inversion

I64 chord inversion is commonly used in music composition and arrangement. It creates a smooth and pleasant sound that can add interest to a piece of music.

One of the most common uses of I64 is in cadences, which are musical phrases that mark the end of a section or piece. In classical music, the I64 chord often appears before the V chord as part of a cadential 6/4 progression.


In summary, I64 refers to a specific type of chord inversion used in music theory. It’s applied to chords built on IV scale degree in major keys and involves placing the third note at the bottom or bass note position while keeping all other notes above it.

Understanding chord inversions and the Roman numeral system is crucial for analyzing and composing music effectively. Incorporating I64 can add depth and complexity to your compositions, making them more interesting and engaging for listeners.