Numbers & science
Musical Notes & Frequencies
Notes, semitones, octaves, MIDI numbers and equal-tempered frequencies, with playable reference tones.
Equal temperament: Each semitone multiplies frequency by 21/12. The default reference is A4 = 440 Hz. Notes an octave higher have double the frequency.
| Note | Enharmonic | MIDI number | Frequency (Hz) | Listen |
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Calculate any note
Sound preview is generated locally with your browser and plays only when a note button is pressed. Scientific pitch notation uses C4 for middle C, MIDI 60.
Geocaching tip: This table helps convert hidden musical-note puzzles into numbers or frequencies. Other tuning systems and historical pitches will not always match A4 = 440 Hz.