What is a Major Thirteenth?

A major thirteenth is a musical interval that spans twenty-one semitones. It can be understood as the distance of a major sixth extended by an octave. For example, the interval between C and A an octave higher is considered a major thirteenth.

Because it is built from a major sixth plus an octave, the major thirteenth has a wide and colorful sound. When used in harmony, it creates a sense of openness and richness that expands beyond the basic triad and seventh chord structures. The large distance between the notes allows the interval to add depth and complexity to musical textures.

Major thirteenths often appear in extended chords, particularly in jazz, soul, and contemporary harmony. For example, a C13 chord may include the notes C, E, G, B♭, D, F, and A, with the A above the octave forming the thirteenth interval from the root. This interval helps create lush and sophisticated chord voicings used in many modern musical styles.