Weight categories in Judo
The Kodokan original technical theory was that Judo was not a weight sport, but fundamentally a technique-oriented sport. Weight and strength were irrelevant. So, at the 1956 World Championships, and the next two World Championships held in Tokyo, and then Paris, in 1961, international competitions were traditional "open" style, with no weight, rank, or age distinctions.
At the 1960 meeting of the International Olympic Committee, Judo was accepted as a demonstration sport for the 1964 Tokyo Summer Olympic Games. This was fitting, as Japan hosted the games in memory of the founder of amateur athletics in Japan, Jigoro Kano. The matches were held in the newly-constructed Nippon Budokan, and consisted of three weight categories, light, middle and heavy, as well as an open category.
The categories were expanded to 6 (including an open category) for the 1972 Olympics, and 8 for the 1980 Olympics. In 1992 the open category was dropped from the Olympics, so there are currently 7 weight categories for both men and women in the Olympics.
In 1964 there were 4 men's weight categories as follows: Lightweight (-63 kg/-139 lbs), Middleweight (-80 kg/-176 lbs), Heavyweight (-93 kg/-205 lbs), and Open weight.
In 1968 there was no Judo event, but in 1972 the event was expanded to 6 men's weight categories as follows: Lightweight (-63 kg/-139 lbs), Half-Middleweight (-70 kg/-154 lbs), Middleweight (-80 kg/-176 lbs), Half-Heavyweight (-93 kg/-205 lbs), Heavyweight (Over 93 kg/205 lbs), and Open weight.
In 1980 it was again expanded, this time to 8 weight categories as follows: Extra Lightweight (-60 kg), Half Lightweight (-65 Kg), Lightweight (-71 Kg), Half-Middleweight (-78 kg), Middleweight (-86 kg), Half-Heavyweight (-95 kg), Heavyweight (Over 95 kg), and Open weight.
In 1992 the Open weight was dropped and there are 7 remaining official weight categories for men. In addition, women's competition was added to the Olympics as an official medal sport with 7 weight categories (after being a demonstration sport in the 1988 Olympics in Seoul, Korea). The number of weight categories stayed the same, but in 1998 the weights for each category were changed to the following:
Actual Weight Categories versus Age
Weight categories and duration of the competition vary with age. The following are the official IJF regulations: