What is an Octave?

An octave is a musical interval that represents the distance between one note and another note with double or half its frequency. When two notes are an octave apart, they have the same name but sound higher or lower in pitch. For example, the note C played on a piano can appear in several different octaves, each one higher or lower than the last.

In Western music theory, an octave spans twelve semitones and includes all the notes within that range. When a musician moves from one note up to the next note with the same letter name, such as from C to the next higher C, they have moved up an octave. The same concept applies when moving downward from a note to the next lower version of that note.

Octaves are important because they help organize musical pitch and structure. Instruments and voices often perform melodies across multiple octaves to create variation and expression. Because notes separated by an octave sound closely related, the octave is considered one of the most fundamental intervals in music.