The designation of middle C varies depending on the context. In scientific pitch notation, middle C is designated as C4, which is the fourth C key from the left on a standard 88-key piano keyboard). In Helmholtz pitch notation, middle C is designated as c′ ). However, in the MIDI standard definition, middle C is labeled as note number 60, and there is no official octave designation for middle C. Some musicians naturally use the term "middle C" to refer to the C note in the middle of their specific instruments range, and this can vary across instruments and clefs). Therefore, the answer to the question "what octave is middle C" depends on the context and the notation system being used.