The Gurney Equations are a range of formulae used in explosives engineering to predict how fast an explosive will accelerate a surrounding layer of metal or other material when the explosive detonates. This determines how fast fragments are released on detonation of an item of ammunition. This initial fragment velocity can then be used with other ballistic equations to predict either danger areas or fragment penetration.

The initial velocity of warhead fragments can be estimated using the Gurney equation.

A general form of the Gurney equation which can be used for different geometries is given in the Gurney equations in this section. It may be used to analytically predict expected fragment initial velocities. These equations assume a uniform but time-varying pressure and density, a linear initial-velocity profile for the accelerating casing, a uniformly distributed explosive, and a uniform thickness of the case.

This calculation uses the following equations:

IATG 01.80 - Formulae for Ammunition Management - Clause 8.1