Muay Thai weight classes

Muay Thai has no single governing body. There is no equivalent of the NCAA, no United World Wrestling, nothing that publishes one list everybody follows. What exists instead is three overlapping systems that happen to reuse the same division names for different weights.

The Thai stadium ladder

Lumpinee, Rajadamnern and the WBC Muay Thai use the boxing division structure, in pounds. The full ladder, with the limits from the WBC Muay Thai rules:

Seventeen divisions, and the naming is not uniform even inside Thailand. Rajadamnern bills its 105 lb title as Minimumweight and 115 lb as Super Flyweight. Older tables use Junior where the WBC uses Super, so Junior Bantamweight and Super-Flyweight are the same 115 lb. Same weight, different word on the belt.

Thailand's competitive depth sits roughly between 108 and 126 lb, because that is where most Thai fighters naturally are. Western promotions cluster higher, and a foreigner at 147 lb is competing in a much thinner domestic field than a Thai at 118.

IFMA, in kilograms

Amateur Muay Thai under IFMA runs metric classes, and these are what appear at the SEA Games, continental championships and IFMA world championships. Confirmed from the 2025 SEA Games programme:

Which of them are actually contested varies by event. At the 2025 SEA Games the men's programme ran 63.5, 67, 71 and 75 kg and the women's ran 45 through 60. Check the entry document for your competition rather than assuming your class is being held.

IFMA also operates under the World Anti-Doping Code, which the professional stadium circuit does not. That is a bigger practical difference than any weight limit. How the two halves of the sport diverge.

ONE, and why the names mislead

ONE Championship runs its own divisions, and this is the part that catches fighters moving between promotions.

A ONE strawweight is not a strawweight anywhere else. The names are shifted upward by two or three rungs against the traditional ladder, so a fighter reading a ONE poster and comparing it with a Rajadamnern card is comparing labels that do not correspond.

Read the third column. A ONE flyweight and a stadium lightweight make the same 135 lb. A ONE bantamweight is heavier than a stadium welterweight. Somebody described as a flyweight in one promotion would be three divisions up in the other, and it is the same body on the same scale.

Which means a ONE division and a stadium division with the same number are not the same target. One of them you reach hydrated over weeks of food. The other you can still reach the old way, and plenty do.

The question that actually decides your class

Not the chart. The weigh-in.

A fighter who takes 2 per cent off in the last two days and weighs in on the morning competes 2 per cent down. There is no version of that arithmetic that improves later in the day.

So before you agree a weight, ask the promoter three things: when is the weigh-in, is there a hydration test, and what happens if the weight is missed. All three have definite answers months in advance and none of them are answerable in fight week.

The problem nobody writes about

Muay Thai fighters compete far more often than boxers. On the Thai circuit that can mean a bout every few weeks, which removes the thing every weight-cutting article assumes: a camp, followed by a period of eating normally.

In professional boxing the published guidance is to sit 12 to 15 per cent above the division limit between camps. That band assumes camps exist and that there is time between them to be a normal weight. Applied to a fighter competing monthly it means nothing.

What replaces it is a narrower operating range held all year. No position stand puts a number on that, so what follows is my own judgement rather than a cited figure. The weight you fight at should be one you can hold within 2 or 3 per cent for months, because you will be asked to make it again before you have recovered from making it last time.

Which turns the question from "can I make this weight" into "can I make it 8 times a year without a phase in between where I eat normally". A fighter who answers yes honestly has a long career available. A fighter who answers yes because he made it once is describing the first two years of a career that ends early.

Before you agree a weight

• Get the promoter's chart in writing. Not the one from your last card.
• Confirm the unit. Thai stadiums work in pounds, IFMA in kilograms, and rounding between them has cost people bouts.
• Confirm the weigh-in time and whether a hydration test applies.
• Then ask whether you can hold that weight through your next four fights, not just this one.

Charts here move more than in any other combat sport on this site, because there is nobody with the authority to stop them moving. Treat everything above as orientation, and the document for your own card as the rule.

Common questions

What are the Muay Thai weight classes?

There is no single set. The Thai stadiums and WBC Muay Thai use the traditional boxing ladder in pounds, 17 divisions from Mini-Flyweight at 105 to Heavyweight over 200. IFMA, the amateur body, uses metric classes: 14 for men and 11 for women, from 45 kg upward. ONE Championship runs 10 of its own, with names that sit two or three rungs heavier than the same names elsewhere.

Does Muay Thai have a governing body?

Not one that everybody follows. IFMA governs the amateur side and operates under the World Anti-Doping Code. The professional stadium circuit in Thailand, the WBC Muay Thai and promotions such as ONE each run their own rules, weight classes and weigh-in procedures.

Why are ONE Championship's weight classes different?

ONE uses its own division names at heavier weights than the traditional ladder, so its strawweight is not a strawweight elsewhere. It also removed dehydration cutting rather than capping the refill: athletes are hydration tested with urine specific gravity required at or below 1.025, and matchmaking works from walking weight.

When do you weigh in for a Muay Thai fight?

It depends entirely on the card. Some stadium bouts weigh on the morning of the fight, leaving no recovery window at all. Others weigh the day before. Hydration-tested promotions weigh in the days beforehand and test as well. Confirm which applies before you agree a weight, because it changes the plan more than the number does.

What weight should a Muay Thai fighter walk around at?

Narrower than a boxer. The published boxing guidance of 12 to 15 per cent above the limit between camps assumes camps with rest phases in between. A fighter competing every few weeks should hold a weight within about 2 or 3 per cent of the one he competes at, all year.