Understanding Density Constants: Metric vs British Inch System — Lesson 2

Why does the density constant not look correct in the Material Properties tab? 

In metric, density is already in mass/volume, but engineers using the British Inch system often are accustomed to using Weight Density. So, for aluminum it is .1 lbf/in^3. Since this is not mass density, one needs to divide by gravity. So, take .1/386.1 and you will have that number.