John, I think you may have misunderstood my question. I realize that the numbers involved will be different from one projector to another. What I'm wondering is if the term "Throw Ratio" is an industry standard term in which this "throw ratio" number, when multiplied by the image width, would provide the necessary throw distance. This is how NEC seems to use this term, but I wasn't sure if any other manufacturers used it.

I believe the answer to this may be "no". While NEC's literature references this "Throw Ratio", Sharp, for instance, does not. In fact, looking at the instruction manual for the Sharp XV-Z7000U, I see that the calculations that they provide for determining throw distance use the image's diagonal size for the calculations. I'm guessing, therefore, that Projector Central's throw distance calculator is the result of their manual effort at converting all of the various manufacturer's calculations into a common formula, as I have suggested (though they may not be using width).

Scott