I don't box or participate in the combative sports so I might be asking a stupid question but please humor me. What is the minimum weight required to box/fight at a specific weight class. I can see all the boxing weight classes on wikipedia here so I know what the UPPER limit is for each class.

For example, if someone boxes at a high level at lightweight (135lbs) and wants to fight someone at heavyweight (200+ lbs) to win the heavyweight championship belt (something worth risking the size mismatch), will any sanctioning body allow this fight to occur even though there's a huge size mismatch between the two fighters?

I always hear fighters after a fight saying they are confident in their skill, they knew they could do XYZ, etc. thus, I could see someone thinking:

"Due to my lighter/smaller frame, I feel I can out-quick someone who fights at heavyweight. My quickness can help me duck/parry/slip his punches and run around him if he tries to corner me. Since I'm lighter, I should be able to box longer without getting tired, etc."

Assuming the lightweight is that skilled, would any boxing sanctioning body allow this fight to take place?

1 Answer 1



"Amateur" boxers cannot fight above (or below) their weight class, as stated by the Amateur International Boxing Association (the seemingly most well-regarded amateur ruling body). The lower bound of a weight class is also a requirement to fight at that weight. Oddly enough, this is also the case for the Summer Olympics.

Source: AIBA, Technical & Competition Rules, §1.2 & Appendix K

Pro boxing is a little trickier, as there are 4 different major boxing organizations - the IBF, WBO, WBA, and WBC. Fortunately, they seem to have more or less the same ideas about minimum weight, namely that there isn't one. A fighter is free to fight above their weightclass as far as I can tell, at least from the WBO and IBF rules.

One thing to note, however, is that to challenge the holder of the heavyweight championship belt, you're going to have to be ranked pretty high within that weight division to even get the chance. That means winning several fights with a pretty drastic disadvantage. In reality, I doubt they'd ever let a fight between fighters of that large a weight discrepancy ever happen. And personally, I'd probably take my extra 80 pounds of pure functional muscle over quickness any day.

There are also "catch weight" fights that have limits outside the usual weight classes. The limit is typically agreed upon by the boxers themselves beforehand.


The MMA has similar rules to amateur boxing (at least in the United States), as athletic commissions from several states came together to write the Unified Rules of Mixed Martial Arts, which states fighters must fight within their weight classes.

  • Thx for the answer. I guess I don't know anything about physiology either. Some of the boxers who box at heavyweight look like they just eat hamburgers and are out of shape. I'm sure they train hard and could run a mile in 4 min, bench press 225lbs 50 times, etc. However, a few fights I saw, the heavyweight boxer tired easily and quickly so I thought perhaps a smaller, lighter, equally skilled person could beat them.
    – Classified
    Commented Jul 6, 2016 at 20:30
  • However, I can understand in grappling sports like wrestling or BJJ, being heavier would be an advantage, even if you are a little less skilled than the lighter person.
    – Classified
    Commented Jul 6, 2016 at 20:33
  • @Classified Fighting is tiring, no matter your size. For equally skilled fighters, the larger one is always going to have an advantage. Hits harder, absorbs punishment more easily, and is tougher to get to the ground. A 150 lb boxer used to fighting others of similar size is going to feel like he's continually getting hit by a truck if he suddenly fights a 250 lb heavy weight. Commented Jul 12, 2016 at 15:57

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