Convert Note to frequency and frequency to note

This plug-in calculates the frequency of a note entered as “Note + Octave”.
For example, entering “A 4” as the note will give a result of 440Hz, assuming “A 440” tuning (A440 (pitch standard) - Wikipedia)

The plug-in also calculates the “Note + Octave” notation for a given frequency.
For example, entering “440 Hz” as the frequency will give a result of “A 4”, assuming “A 440” tuning.

Note values are represented as “Note + Octave + Cents”.
A “Cent” is 1 hundredth of a tone.

The plug-in also supports non-standard tuning in the range A4 = 430 Hz to A4 = 450 Hz (default A4 = 440 Hz).

The verbosity of the output can be changed, which may be useful if you need to quickly copy and paste multiple conversions.

Note that on Windows (and perhaps Mac OS X ?) it is not possible to select and copy from the returned message window, but if you click on the “Debug” button rather than the “OK” button, a second “debug” window will open after closing the message. The result from this plug-in is duplicated in the debug window and this may be selected and copied. This is not usually necessary on Linux as the normal message can be selected and copied using a mouse, but may still be useful for keyboard only operation.


  • Note: [C, C# / Db, … B] (defaut C) The note letter to be converted to a frequency.
  • Octave: [0 to 8] (default 4) The note octave.
  • Frequency (Hz): [1 to 8000] (default 440) The frequency to be converted to a Note.
  • Show output as: [Select the verbosity of the output] (default “Full details”)
  • A4 Tuning (Hz): [430 to 450] (default 440 Hz) The tuning standard to be used.

Example of “Full detail” output:

For equal-tempered scale, A4 = 432.00 Hz:

The frequency of C 4 is 256.87 Hz.

The closest note to 440.00 Hz is A 4.
440.00 Hz is A 4 +31.77 Cents.

Additional information:
Note/ Frequency conversion tables are available on-line here: Frequencies of Musical Notes, A4 = 440 Hz

Installation Instructions:

Note that this is a “Generate” type plug-in (even though it does not actually “generate” anything) and will appear in the “Generate” menu. Hopefully Audacity will eventually have a “Tools” menu.
note-frequency.ny (2.66 KB)
Please let me know if you find this plug-in useful by posting a reply.
Questions and/or bug reports relating to this plug-in should also be posted here.

I thought from its name it was also doing pitch detection, so I was confused at first.

This is a “tool”. If we ever have a “Tools” Menu, would a future iteration of Nyquist plug-ins be able to go in there without generating a track?


FWIW, a fair number of Audacity tutorials that show how to use Audacity to convert from 440 Hz to 432 Hz state that you should convert to “432.186 Hz”.

I don’t know why, any more than why 432 Hz is in accordance with the mathematical patterns of the universe, but you “might” get people wanting 3 decimal places.


Yes, definitely a “tool” rather than an “effect”, “generator” or “analyser”.
If we ever have “Tools” (or “utility”) type Nyquist plug-in, it should be able to run without requiring a track selection and without generating a track.

If it were in the Analyze menu, then yes I agree that the name would be highly suggestive of pitch detection.
In the Generate menu I think the name suggests that it will generate “notes”. Perhaps I could add that as an option.

One disadvantage of the Effect and Analyze menus are that they require a selection. Also, they strongly suggest* that it will process or analyze the selection in some way (* More that “strongly suggest” - that is the stated purpose of “analyze” and “process” type plug-ins).

Taking into account that it has to go into one of Generate, Effect or Analyze menus, can you think of a better name?

The difference between 432.186 and 432.19 Hz is 0.0160 Cents. That is just a little over 0.0003 of a semi-tone.

Quoting from: Cent (music) - Wikipedia

so the difference between 432.186 Hz and 432.19 Hz is around 60 times smaller than a difference that is “much too small” to hear. :open_mouth:

The plug-in is licensed GPL v2, which allows users to modify it to suit their needs. I don’t think that GPL differentiates between the rights of humans, illuminati or lizards.

There is a “Windows way” which works on some dialogues and does actually work with the Nyquist information dialogues (so also captures the text of Nyquist “Help Screens”). Just CTRL + C and the window title and contents are copied to the system clipboard.


For equal-tempered scale, A4 = 438.20 Hz:

The frequency of C# / Db 4 is 276.05 Hz.

The closest note to 440.00 Hz is A 4.
440.00 Hz is A 4 +7.10 Cents.


For other dialogues there are various tools like WinScraper: 8 Ways to Copy Error Messages from Window or Message Box .

If I get a chance I’ll post if the output of your tool can be captured on Mac.


On Linux, the content of a Nyquist “returned text” window can be copied using keyboard control only:

  1. Tab
  2. Ctrl+C

After that, to “OK” the dialogue from the keyboard, “Tab” then “Enter”.

I think it is more appropriate in Generate, given there is no Tools menu.

I can’t think of a better name without adding “Conversion” or “Tool” to the name.

An option to generate the note might be fun if it took into account the tuning. However you might want to increase the upper end of the slider range?


You’re probably missing the point. The difference may be in how it vibrates your soul.


Proponents of the theory claim that it works with real music played by real instruments. Given that real instruments never achieve anywhere near that degree of pitch accuracy, the soul must be a bit flexible about what it vibrates to. Has anyone worked out if the universe uses equal temperament?

Have you noticed the “interference beats” between a “perfectly tuned” A and an E ? or that a well tuned piano is slightly sharper at the top (high) end of the scale than the low end?

This image is from a book about piano tuning and illustrates “a plot of actual measurements of a piano tuned by a skilled tuner, along with a curve resulting from the average of many such measurements:”

Notice how the top C is about a semitone sharper than the bottom C. This is called “stretching” and is required on (real) pianos to prevent “partials” from clashing,

Most keys have been labelled with properties like triumphant, sombre etc.
A lot of people lay down an oath that they do hear those differences in the mood when listening to compositions, modern or classic.
The problem is that e.g. at Mozarts time the tuning could be as low as 418 Hz. Thus those colourful descriptions are actual referring to keys almost a semi tone lower.
As with all beliefs, people hear what they want to hear and are remarkably persistent in convincing themselves that they have found the only truth.