Frequency of a note

How to use the note frequency tool

Select a note on the first row, then optionally choose a sharp or flat note on the second row. The tool uses equal temperament, so enharmonic notes such as C♯ and D♭ have the same frequency.

Then choose the octave with the − and + buttons. The corresponding frequency is calculated automatically in hertz.

A4 reference

The A4 reference defines the starting point for tuning. By default, the tool uses A4 = 440 Hz, which is the most common reference.

Changing this value changes all calculated frequencies because the other notes are derived from that base frequency.

Natural notes and enharmonic notes

The first row contains the seven natural notes: C, D, E, F, G, A, and B. The second row contains the five notes between them, such as C♯/D♭ or F♯/G♭.

In equal temperament, both names refer to the same frequency. That is why they are grouped together in this simple tool.

Equal temperament

This tool uses equal temperament, where the octave is divided into twelve equal semitones. It is the most common system for pianos, synthesizers, audio software, and many modern instruments.

Simple or advanced version?

This version is designed to quickly get the frequency of a note. To compare several temperaments, distinguish some sharps and flats, or listen to a synthesized sound, use the advanced version.

Data and privacy

The calculation runs directly in the browser. The selected note, octave, and reference are not sent to the server to use the tool.