Ballistic coefficient is an index of the manner a particular projectile decelerates during flight. It represents a bullet’s ability to overcome air resistance during flight.

It is expressed mathematically as:

where:

= ballistic coefficient,
= mass, in pounds,
= coefficient of form (aka form factor),
= bullet diameter, in inches.

Footnotes / Sources:

“Glossary ⇒.” Sporting Arms and Ammunition Manufacturers’ Institute. Ed. SAAMI’s Technical Committee. Web. 15-18 Jan. 2011.