Last updated: 3 October 2026
Reviewed by Jordan Morley, FA Level 2 Football Coach
MMA weight classes ensure fair competition between similarly-sized fighters. The UFC recognises 8 men’s and 4 women’s weight classes. Weight cutting — dehydrating before weigh-ins to compete in a lighter class — is controversial; ONE Championship now uses hydration testing to prevent it. Most competitive MMA fighters walk around 5-10% above their fight weight. Moving up (or down) a weight class is a common strategic decision as careers develop.
- 8 men’s and 4 women’s UFC divisions
- Strawweight 52.2 kg to Heavyweight 120.2 kg
- Weight cutting is common but controversial
- ONE Championship uses hydration tests
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MMA weight classes exist to create competitively fair matchups given how significantly size and weight affect striking power and grappling leverage — fighters typically cut weight aggressively in the final days before a weigh-in to compete in a lower class than their natural walking weight, then rehydrate before fight night, a controversial practice that has driven ongoing debate about same-day weigh-ins and fighter safety.
FAQ
Why do MMA fighters cut so much weight before fights?
Cutting weight (often through dehydration) lets fighters compete in a lower weight class than their natural size, aiming to face opponents who are naturally smaller once both fighters rehydrate after the official weigh-in.
Has weight cutting caused changes to MMA weigh-in rules?
Yes — concerns about extreme weight cutting have led some promotions to adopt additional weigh-in checkpoints or same-day/early weigh-ins to reduce the health risks of rapid dehydration-based weight cutting.