All velocity data was calculated and then rounded up to the next-higher foot per second if an integer result was not obtained.

Power Factor = Bullet Velocity in feet per second multiplied by Bullet Weight in grains (7000 grains = 1 pound).

Using the metric system, Power Factor = Bullet Velocity in meters per second multiplied by Bullet Weight in grams, multiplied by a conversion factor of 50.631 (1 meter per second = 3.280839895 feet per second, 1 gram = 15.432358353 grains).  For example, a 14.9 gram bullet at 219 meters per second yields a power factor of 165,214.

Students of physics will note that because the IDPA power factor formula calls for a simple product of mass and velocity ( P = M x V ), the IDPA power factor is a representation of momentum, rather than kinetic energy ( E = M x V² / 2 ).

Also note that in informal usage, it is fairly common for shooters to drop the "thousands" when discussing power factors.  For example, the phrase "125 power factor" will almost always refer to a power factor of 125,000.