Given the projectile weight, diameter, Ballistic Coefficient and the relevant Drag Law, this app details the Sectional Density, Form Factor, Projectile Drag Coefficient and Reference Drag Coefficient (relative to the particular velocity, Ambient Temperature and Drag Law).
This can be useful in estimating BC values of projectiles of similar form but having different mass and/or calibre.
i.e., by assuming the same Form Factor can be applied.

An email-able Drag-law graph and table are also supplied.