The official distance of a marathon race is 42.195 kilometers or 26 miles and 385 yards. The distance was standardized by the International Amateur Athletic Federation (IAAF) in May 1921, after years of having it bumping around between 24 to 26 miles. The exact length of the marathon was not precisely fixed at first, but the marathon races in the first few Olympic Games were about 40 kilometers (25 miles), roughly the distance from Marathon to Athens by the longer, flatter route. The distance became standardized in the 1908 London Olympics, where the royal family requested that the race start directly in front of Windsor Castle and finish right in front of the royal viewing box, adding 385 yards to the original 26 miles.