Density Calculation

Weigh a piece of it whose volume can be easily calculated. Divide weight by volume. (This is the definition of density for any particular substance, steel or otherwise.) Depending on the alloy, steel is about 490 lb/ft³.

(Rather than calculating it, one usually looks it up in materials data and uses it for some other calculation.)

If your sample has a volume difficult to measure, just put it in a container full of water and measure the volume of waterwhich overflows.

Even simpler just google "density of ('insert your material here')"
Del

One calculates one's way into Kempe's Engineers' Yearbook, any edition, and looks it up.