Pitch & Frequency
Adjustable A4 and C0–C10 table
Most ensembles use A4 = 440 Hz as the international standard; some groups use 442 Hz or 444 Hz for a brighter sound. Adjust A4 below and every row in the table updates.
Note: this only changes the reference pitch; equal temperament is unchanged (semitones stay 100 cents apart). Live intonation also depends on temperature, instruments, and technique.
Notes are grouped by octave, using scientific pitch notation for note names (e.g. C4, A4). Tap a row or card to hear 1 s pure tone; a highlighted row means it is playing.
Note: The lowest and highest rows (e.g. C0, C10) sit near the edge of hearing; many speakers cannot reproduce them cleanly. If you hear little or only distortion, that is usually hearing and hardware limits, not a calculation error.
Frequencies use equal temperament: f(n) = A4 × 2^((n − 69) / 12) where n is the MIDI note number (A4 = 69) and A4 is your reference above. Names use sharps (C♯ not D♭); scores may show enharmonic equivalents.