Thanks, Nate. With only one exception, all the tunings I've used go low to high, which would eliminate some of those possibilities. The only exception was Eb D F# A.
Just to clarify, there should easily be over 1200 tuning combinations where each string has a higher pitch tone than the next lowest string. If we assume a standard 4 string tuning like ADad, and that each note could be down tuned by three steps, or uptuned by two, that still leaves 6 individual notes that each string could be tuned to. For an A string, this could be F#, G, G#, A, A#, or B. For a D string this could be B, C, C#, D, D#, or E.
So since 6 individual notes are available per string, 6x6x6x6=1296 tuning schemes. Of course, there are way more than 6 half steps available for string, making the number much higher than 1200, not lower. In fact, Eb, D, F#, A is not in the 1200 that I mentioned, just based off the starting point of ADAd and only 6 steps of freedom.
updated by @nate: 08/18/25 05:45:03AM