

UFC, for example, recognizes women's titles in the strawweight, flyweight, bantamweight and featherweight classes. Weight limits in women's MMA mostly follow the Unified Rules' limits, but organizations that recognize women's championships usually only have titles at the lower end of the table. However, due to the increasingly competitive and international nature of the sport, weight limits have been set by the promotions themselves usually in alignment with the Unified Rules, as maintaining standard weight classes is seen as fair and standard for all competitors. With no state or government laws regarding weight class restrictions, organizations in other countries are free to schedule bouts with little regard for weight differential. The super lightweight, super welterweight, super middleweight, and cruiserweight classes were added in July 2017. The Unified Rules designate limits for fourteen different weight classes in mixed martial arts all definitions and measurements are in pounds. For a promotion to hold mixed martial arts events in a state-sanctioned venue, the promotion must abide by the state athletic commission's body of rules for weight limits.

Since then, to create uniformity, all state commissions in the United States that regulate mixed martial arts have assimilated these rules into their existing unarmed combat competition rules and statutes. California officially sanctioned MMA on December 28, 2005, using the ruleset it helped devise five years previously. The California State Athletic Commission had worked extensively on regulation, but their sanctioning of MMA was not implemented due to state governmental issues surrounding the process. In 2000, the Unified Rules of Mixed Martial Arts were codified by the New Jersey State Athletic Commission.

Weight classes underwent many changes in the ensuing years, but the ability of promotions to autonomously decide their own weight classes eventually disappeared after athletic commissions began supervising mixed martial arts. For instance, the Ultimate Fighting Championship introduced two weight classes at UFC 12: heavyweight, which grouped competitors above 200 lb (91 kg), and lightweight, which grouped competitors under 200 lb. Prior to state sanctioning, weight classes were not mandatory since the competitions were held without the approval of the athletic commissions.
