In ballistics, the ballistic coefficient (BC) of a body is a measure of its ability to overcome air resistance in flight. It is inversely proportional to the negative acceleration — a high number indicates a low negative acceleration. BC is a function of mass, diameter, and drag coefficient. It is given by the mass of the object divided by the diameter squared that it presents to the airflow divided by a dimensionless constant i that relates to the aerodynamics of its shape. Ballistic coefficient has units of lb/in² or kg/m². BCs for bullets are normally stated in lb/in² by their manufacturers without referring to this unit.
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