Muay Thai Weight Classes Under IFMA Rules Explained
Muay thai weight classes under IFMA rules run from 45 kg up to over 91 kg for men and over 75 kg for women. See every limit and how weigh-ins work.
Muay thai weight classes sort athletes into divisions by body weight. Under the IFMA Rules and Regulations, elite men compete in classes from 45 kg (45 kg only at selected multi-sport events) up to over 91 kg, and elite women in classes from 45 kg up to over 75 kg. Each class has an upper limit, and athletes have to come in at or under it when they weigh in.
The lists below are taken from the IFMA Rules and Regulations, the rulebook IFMA uses for international competition. Other organisations set their own divisions and limits, so these numbers apply to IFMA-sanctioned events only.
Why Weight Classes Matter
Weight classes group athletes of similar size so that contests are fairer and safer.
In IFMA’s rules, an athlete’s weight class is set at the official weigh-in. A national team can put forward only one athlete in each division.
IFMA Weight Classes for Elite Men
Under IFMA rules, the men’s classes for the Elite and Masters age groups have these upper limits:
- 45 kg (used only in selected multi-sport events, if the IFMA Executive Committee approves)
- 48 kg
- 51 kg
- 54 kg
- 57 kg
- 60 kg
- 63.5 kg
- 67 kg
- 71 kg
- 75 kg
- 81 kg
- 86 kg
- 91 kg
- Over 91 kg
Athletes in the Masters 40+ and Masters 45+ groups cannot enter the over 91 kg class. The U24 category uses the same men’s limits.
IFMA Weight Classes for Elite Women
The women’s classes for the Elite and Masters age groups have these upper limits:
- 45 kg
- 48 kg
- 51 kg
- 54 kg
- 57 kg
- 60 kg
- 63.5 kg
- 67 kg
- 71 kg
- 75 kg
- Over 75 kg
The U24 category uses the same women’s limits. Up to 75 kg, the women’s limits are identical to the men’s. Above that, the women’s list ends with an open class over 75 kg, while the men’s list continues to 81, 86 and 91 kg before its own open class.
Youth Divisions
IFMA sets separate weight lists for each youth age category, from U18 down to U8. The U18 lists are close to the senior ones, while younger categories start lighter and use smaller steps, down to 16 kg for U8.
A few examples from the IFMA tables:
- U18 boys: the same limits as the elite men’s list from 45 kg up, ending with an open class over 91 kg.
- U18 girls: a lighter first class at 42 kg, then the elite women’s limits up to an open class over 75 kg.
- U14: classes start at 32 kg and rise in 2 kg steps through the lighter divisions.
- U8: the lightest class is 16 kg.
IFMA places athletes in age categories by year of birth, not by their exact birthday. Check the full table in the rulebook for the right category before entering a youth athlete, because the limits and the number of classes change at each level.
How Weigh-Ins Work
The IFMA rulebook sets out three kinds of weigh-in:
- Official weigh-in: held the day before competition starts, when the Technical Delegate calls for it. The weight recorded there decides the athlete’s class for the whole event.
- Competition weigh-in: held on the morning of each competition day, to check that the athlete is still inside the limit.
- Pre-contest weigh-in: can be carried out at any point before or after a bout.
Key rules from the rulebook:
- A doctor must clear each athlete as fit on every competition day, right before they step on the scales.
- Athletes weigh in wearing light underwear and already prepared to compete.
- Each athlete gets one attempt on the official scales per day, and the reading from that attempt stands.
- Missing the weigh-in means automatic disqualification.
- Failing to make the class, or failing the medical check, means the athlete loses by walk-over.
- In a pre-contest check, an athlete who weighs 5% over their qualified class, or who reaches the limit of the next class up, is disqualified.
Bouts begin at least three hours after the competition weigh-in closes. Officials can allow a shorter gap only after consulting the medical commission.
Reading the Lists Correctly
Keep these points in mind when you use the IFMA lists:
- Every number is an upper limit. An athlete in the 60 kg class must weigh no more than 60 kg.
- The two open classes, over 91 kg for men and over 75 kg for women, have no upper limit.
- The 45 kg men’s class appears only at selected multi-sport events.
- Under IFMA rules, weight is checked on each competition day, so athletes have to stay inside their limit for the whole event, not just one morning.
- Other organisations publish their own lists, so a limit used in one event may not exist in another.
Frequently Asked Questions
How many weight classes are there in IFMA muay thai?
The IFMA list for elite men has 14 classes, one of them a 45 kg class used only at selected multi-sport events. The elite women’s list has 11 classes. Youth categories each have their own lists.
What is the heaviest weight class in muay thai?
Under IFMA rules, the heaviest men’s class is over 91 kg and the heaviest women’s class is over 75 kg. Neither open class has an upper limit.
Do all muay thai organisations use the same weight classes?
No. The limits in this article come from the IFMA Rules and Regulations. Other organisations set their own divisions, so check the rulebook of the event you plan to enter.
