B3
Reviewed for accuracy · Maintained by Justin Evans
B3 highlighted — use the view toggle to see all 88 keys.
Piano key
39 of 88
Octave
3
Frequency
246.94 Hz
MIDI number
59
Key color
White key
Pitch class
B · Cb · A##
What is B3?
B3 is the B in octave 3 — the 39th key of the 88 on a full-size piano, counted from the bottom. In standard tuning it sounds at 246.94 Hz. It sits 1 half-step below middle C (C4).
To find it, locate any group of two black keys: the white key just to their left is a C. Count down from middle C (C4) 1 octave to reach octave 3, then step to B.
Every octave doubles the frequency: the B one octave up sounds at 493.88 Hz and the one below at 123.47 Hz. The same piano key can be written as B, Cb, A## depending on the musical context — same sound, different spelling.
Nearby notes
Every B on the keyboard: