Pitch reference
MIDI note finder
Enter a note number to see its common name and equal-tempered frequency.
C4261.63 Hz at A4 = 440 Hz
Uses twelve-tone equal temperament. This tool names MIDI note 60 as C4; octave labels vary between manufacturers and apps.
About octave labels
MIDI carries a note number, not an octave name. Some manufacturers label middle C differently. Check the number when comparing devices; this tool uses C4 for note 60.