Note Frequency Reference
Look up and hear the exact frequency in Hz for any note and octave, at standard A4 = 440Hz or another tuning pitch.
About this tool
Frequencies are calculated as 440 × 2(n−69)/12, where n is the note's MIDI number — the standard formula for 12-tone equal temperament with A4 tuned to 440Hz.
Change the tuning if you play with an ensemble that tunes differently: many European orchestras tune A to 442 or 443 Hz for a brighter sound, period-instrument Baroque groups use 415 Hz (about a semitone lower), and some musicians prefer 432 Hz. Middle C is C4 (about 261.63 Hz at standard pitch). The MIDI number is what music software and keyboards use for each note, and the wavelength tells you roughly how long the sound wave is in air at room temperature, which is useful for speaker and room acoustics.