What is the internationally recognized standard distance of a full marathon race?

💡 Explanation:

The official distance for a marathon was standardized at 42.195 kilometers (26 miles 385 yards) by the International Amateur Athletic Federation (IAAF) in 1921, primarily to accommodate the distance run in the 1908 London Olympics from Windsor Castle to the Olympic Stadium, plus a lap around the track to finish in front of the Royal Box.