Tuning Frequency Calculator

What is this tool?

Equal-temperament pitch math with an adjustable reference A4 (standard 440 Hz, or alternate tunings like 432 / 442). Convert any note name and octave to frequency in Hz, or enter a measured frequency to see the nearest note and how many cents sharp or flat it is. Sharp/flat spelling preference is selectable.

How to use it

1. Set the reference A4 in Hz (440 is concert pitch).
2. Pick a note and octave to read its frequency — or switch modes and enter a measured Hz.
3. In cents mode, see the nearest note and sharp/flat offset.