An investigation was done on three published expanded equations, that convert (T) to (D). T. Celio, J. Altman and M. Abouelata published equations of the same form, but with differing constants. Their equations were derived by using an assumed square-wave transmittance trace. The investigation was to find the best predictor of (D) from (T) . Both practical and simulation tests were run. The density range was extended, to check for failure at both high and low densities. Standard granularity measurement procedures were followed as close as possible. Results, from the practical tests, showed Altman \u27s equation the best predictor of (D). Celio\u27s was a close second, while Abouelata\u27s was a distant third. The simulation test, was run with normal distributions and rectangular distributions. Altman\u27s equation best fit both kinds of density distributions, as well as combinations in between the two
