What are the official NATO caliber rounds for rifle and pistol?

The official NATO caliber round for rifles is the 5.56×45mm NATO, commonly used in assault rifles like the M4 and FN SCAR. For pistols, the standard NATO caliber is the 9×19mm Parabellum, widely used in sidearms such as the Beretta M9 and the SIG P320. These calibers ensure interoperability among NATO member forces during joint operations.