The bantamweight division in mixed martial arts refers to a number of different weight classes:
The bantamweight division sits between the lighter flyweight division and the heavier featherweight and/or lightweight divisions.
Ambiguity and clarification
For the sake of uniformity, many American mixed martial arts websites refer to competitors between 126 and 135 lb (57 and 61 kg) as bantamweights, This encompasses both the Shooto Featherweight division (132 lb / 60 kg) and the King of the Cage Flyweight division (135 lb / 61 kg). The UFC uses the Nevada definition of "bantamweight".
Prior to UFC 31, 150-pound (68 kg) fighters were known as bantamweights in the Ultimate Fighting Championship. After which, the weight limit was raised to 155 lb (70 kg), and the division became reinstated as the lightweight class.
The bantamweight limit, as defined by the Nevada State Athletic Commission and the Association of Boxing Commissions is 135 lb (61 kg).
These tables are not always up to date. Last updated on December 30, 2016.