All rankings are calculated, not measured.
Parameters for calculations include handgun manufacturer's specifications for barrel length, overall length and weight, as well as cartridge ballistics as measured by SAAMI (Sporting Arms and Ammunition Manufacturers' Institute). For a given cartridge there may be a number of bullet weights that are commercially available. To determine a representative cartridge value to use for each caliber we collected muzzle velocity and bullet weights from the range of commercially available cartridges for a given caliber. We then took the mean bullet weight (the nearest actual bullet weight to the average of all bullet weights available for that caliber) and the average muzzle velocity from the same range of commercially available cartridges.
Caliber specification: mean grain weight and average muzzle velocity
Power Factor (PF)
Cartridges listed in our Basics
section are ordered based on the IDPA (International Defensive Pistol Association) Power Factor calculation, which is simply a number generated by multiplying the cartridge's SAAMI measured muzzle velocity times the bullet's mass. (PF = mv x gr). A handgun's Power Factor is the same calculation, but adjusted for the difference between the handgun's actual barrel length and the SAAMI test barrel length.
For defense purposes you want a higher Power Factor.
Recoil Factor (EG)
The Recoil Factor is a measure of the kick-back that a handgun gives you when fired. It is measured in foot-pounds (ft-lb). It relies on the previous specifications and calculations. We use a public domain Standard Free Recoil
equation to calculate recoil.
For defense purposes you want a low Recoil Factor.
Total capacity is the maximum number of cartridges a loaded handgun can hold. For revolvers and derringers this is the number of chambers in the gun. For semi-automatic pistols is is the number of cartridges the gun's standard magazine can hold plus one in the chamber. We do not take into account any extended magazines that a gun may use.
For defense purposes you want a higher Capacity.
While it would be preferable to use all dimensional information to calculate a handgun's relative concealabity (length, width, height, weight), unfortunately only half of the handguns in our database have specifications for width and height. Many manufacturers simply do not provide width and height measurements, and it is often difficult to find that information for older discontinued models in our database. What is ultimately consistent with all handguns we add to the database, at a minimum is overall length and weight. So, we use these two parameters to calculate a relative Concealability factor between guns. The calculation is simply the length in inches plus the weight in pounds (length + (weight/16)). The smaller this number is, the higher the Concealibity factor.
For defense purposes you want a higher Concealability factor.
The Defense Factor is calculated as a derivative sum of the previous four factors. First, each gun's factors are normalized to a percentage value where the highest value of all guns is 100% and the lowest value of all guns is 1%. Once equalized to a percentage they are weighted by an importance scale and summed together: Defense Factor = (Power% * 0.6) + (Capacity% * 0.4) + ((100% - Conceal%) * 0.3) - (Recoil% * 0.3)
Of course, ultimately you want a higher Defense Factor.