Ganesh Rao launches guitar string gauge finder


Ganesh Rao has recently launched an application that allows you to see what gauge of string is required for different tunings, and convert gauges between them. It can be found on his website. This application also lets you add the amount of strings being used, for those who may use guitars with more than six strings. A cover of the song 'Kolaveri Di' was posted earlier.

View the application on

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The problem being solved by the application is to "determine the string gauges needed to maintain identical string tension".
The fundamental frequency of a string under tension is given by:

f1 = sqrt[T/mu]/(2L)

where T is the tension (force), mu is the mass density (i.e. mass per unit length), and L is the length of the string. The mass density term is a linear function of the string diameter (or gauge). By supplying the app with your current tuning and string gauge you are fixing f1 and mu, which allows the app to back out the term:


Notice this term contains information about the tension and the length (i.e. the factors that we want to keep the same). Once you supply the tuning you want to change to, there is a new f1. Now, we have all the terms we information we need to back out mu -- which will lead us the EXACT string gauge to produce these conditions. Then you can simply round this answer to the nearest ACTUAL string gauge that you can buy.

tl;dr -- Since tension and string length are assumed invariant, we can say the answers do not depend on string length.

I can't know for sure that this how his process works, but this is certainly how I would do it.

Well...well done dbilidb!

Wasn't our spot, dbilidb reported it Smile

That is the argument isn't it? Which string company produces the better quality of strings over your duration of play? A longer scaled guitar exposes the weaknesses of a company at tighter tensions.!? Some say so, some say not! In any event, nice spot

Good call, I guess he just 'factored out' that variable by requiring you to specify your current gauges and tuning.
I suppose the relation between tension and string gauge is not affected by the scale length, or only insignificantly (but that's speculation on my part).

I like it but what about scale length?

Thank you! I've was looking for one of these a few days ago!