D (musical note)

${ \new Staff \with{ \magnifyStaff #3/2 } << \time 2/1 \override Score.TimeSignature #'stencil = ##f { \clef bass d1_D \clef treble d'_D } >> }$

D^[1] is a musical note a whole tone above C, and is known as Re within the fixed-Do solfege system. Its enharmonic equivalents are C (C-double sharp) and E (E-double flat). It is the third semitone of the solfège.

When calculated in equal temperament with a reference of A above middle C as 440 Hz, the frequency of middle D (D₄) is approximately 293.665Hz.^[2] See pitch for a discussion of historical variations in frequency.

Designation by octave

Scientific designation	Helmholtz designation	Octave name	Frequency (Hz)
D₋₁	D͵͵͵ or ͵͵͵D or DDDD	Subsubcontra	9.177
D₀	D͵͵ or ͵͵D or DDD	Subcontra	18.354
D₁	D͵ or ͵D or DD	Contra	36.708
D₂	D	Great	73.416
D₃	d	Small	146.832
D₄	d′	One-lined	293.665
D₅	d′′	Two-lined	587.33
D₆	d′′′	Three-lined	1174.659
D₇	d′′′′	Four-lined	2349.318
D₈	d′′′′′	Five-lined	4698.636
D₉	d′′′′′′	Six-lined	9397.273
D₁₀	d′′′′′′′	Seven-lined	18794.545