Note → frequency (Hz)
Pick the note, octave and tuning: get the frequency in Hertz and the corresponding MIDI number.
What it's for
Each note maps to a precise frequency: standard A4 is 440 Hz. Handy for tuning instruments, sound design and understanding music theory.
Tuning 440 or 432
The international standard is 440 Hz. Some prefer 432 Hz, considered «softer»: here you can choose both.