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C2 · 65.41 Hz

C2 is piano key 16 of 88 and MIDI note 36 - the bass register, where bass lines and a male bass voice live. Play the pure tone below, tune to it, or explore the note in every octave.

65.41Hz

Volume50%

Waveform

C2 at a glance

Frequency

65.41 Hz

Wavelength (in air)

5.24 m

MIDI note

36

Piano key

16 / 88

Octave

2

Enharmonic

—

All values assume twelve-tone equal temperament at the international standard pitch of A4 = 440 Hz. In that system every semitone has the same size - a frequency ratio of 2^(1/12) - so C2 is exactly 440 × 2^(-33/12) Hz. Under alternative references the note shifts with the reference: at A4 = 432 Hz, C2 becomes 64.22 Hz.

C in every octave

Note	Frequency	MIDI	Piano key
C1	32.70 Hz	24	4
C2 ←	65.41 Hz	36	16
C3	130.81 Hz	48	28
C4	261.63 Hz	60	40
C5	523.25 Hz	72	52
C6	1046.5 Hz	84	64
C7	2093.0 Hz	96	76
C8	4186.0 Hz	108	88

Each octave doubles the frequency - the simplest relationship in music, and the reason notes an octave apart sound like “the same note, higher”.

Neighboring notes

A♯1 · 58.27 Hz B1 · 61.74 HzC2 · 65.41 HzC♯2 · 69.30 Hz D2 · 73.42 Hz

One semitone down is B1 at 61.74 Hz; one semitone up is C♯2 at 69.30 Hz. Need a frequency between notes, or a different waveform? The tone generator plays anything from 20 Hz to 20 kHz; the note ↔ frequency converter does the math both directions, and the chromatic tuner listens to your instrument and shows the offset in cents.

C2 FAQ

What frequency is C2?

C2 is 65.41 Hz in twelve-tone equal temperament with the standard reference of A4 = 440 Hz. Every semitone step multiplies the frequency by the twelfth root of two (about 1.0595), and C2 sits 33 semitones below A4.

What MIDI number and piano key is C2?

C2 is MIDI note 36 and key 16 of 88 on a standard piano. Octave numbering follows scientific pitch notation, where middle C is C4 (MIDI 60).

How do I tune to C2?

Play the tone above and match your instrument by ear until the beating between the two pitches slows and disappears, or use the chromatic tuner with your microphone for a cents readout. Small mistunings show up as slow beats: one beat per second at this pitch means you are about 26.3 cents off.

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