Scope Numbers Explained: What Every Shooter Should Know

When you look at figures like 3‑9x40 or 4‑16x50 , you’re seeing what are known as scope numbers . Understanding these details is essential for picking the right rifle scope that fits your shooting needs. What Do Scope Numbers Mean? The first part— 3‑9x in 3‑9x40 —refers to magnification . A variable power scope like this allows you to zoom between 3× and 9×. By contrast, a fixed power scope such as 4x32 offers a single, fixed magnification—simplifying use and often reducing weight. The Role of Objective Lens Size The second number, for instance 40 in 3‑9x40 , indicates the objective lens diameter in millimeters. A larger objective lens collects more light, improving brightness and clarity— especially in low-light situations . However, bigger lenses can increase overall weight and raise the scope height on your rifle. Why Eye Relief, Field of View & Exit Pupil Matter Asid...