Which of the following describes CEP?

• A. Circular Error Probable is the maximum distance between DPI and any impact
• B. Circular Error Probable is the radius of a circle with the center at the desired point of impact (DPI)
• C. Circular Error Probable is the standard deviation of impact points
• D. Circular Error Probable is the diameter of the target area

Answer: (B)

CEP is a measure of accuracy that describes how close impact points tend to land relative to the intended point. It represents the radius of a circle centered on the desired point of impact (DPI) that contains 50% of the impact points.

So, Circular Error Probable is the radius of that circle around the DPI where half of the projectiles are expected to fall. This distinguishes it from being the maximum distance any hit could be from the DPI, which would be a different, less representative metric. It also isn’t the standard deviation of the impacts, which describes spread in a statistical sense but not the specific 50% containment. And it isn’t the diameter of the target area; CEP is a radius, not a diameter. If CEP is, say, 50 meters, half of the rounds land within 50 meters of the DPI.