Boxing Weight Classes Explained (Pro, Amateur and Muay Thai)

In July 2020 a six-year-old from Cheyenne, Wyoming, called Bridger Walker stepped between his younger sister and a charging dog and took ninety stitches to the face for it. The World Boxing Council sent the boy an honorary championship belt and then did something no sanctioning body had done in more than thirty years: it created a new weight class and named it after him. Bridgerweight, 200 to 224 lb, exists only in the WBC's rule book, and the other three major bodies have politely declined to notice it. That is boxing's weight system in one story: precise numbers, an irregular history, and four organisations that do not always agree.

The short answer: seventeen divisions, from minimumweight at 105 lb (47.6 kg) to heavyweight, which begins above 200 lb (90.7 kg) and has no ceiling. Amateurs weigh in kilograms, fight in fewer classes and change them every Olympic cycle. Here are the numbers, where they came from, why one limit can have three names, and how to choose yours.

Key facts

Professional divisions

17, recognised by the WBA, WBC, IBF and WBO

Lightest and heaviest

Minimumweight 105 lb (47.6 kg); heavyweight over 200 lb (90.7 kg)

WBC only

Bridgerweight, 200–224 lb (90.7–101.6 kg), since 2020

The original eight

Fly, bantam, feather, light, welter, middle, light heavy, heavy

Paris 2024 Olympic classes

Seven for men, six for women, in kilograms

Weigh-in

The day before for professionals; the morning of the bout for amateurs

Seventeen divisions, one table

Division	Also called	Limit (lb)	Limit (kg)
Minimumweight	Strawweight, mini flyweight	105	47.6
Light flyweight	Junior flyweight	108	49.0
Flyweight	–	112	50.8
Super flyweight	Junior bantamweight	115	52.2
Bantamweight	–	118	53.5
Super bantamweight	Junior featherweight	122	55.3
Featherweight	–	126	57.2
Super featherweight	Junior lightweight	130	59.0
Lightweight	–	135	61.2
Super lightweight	Junior welterweight, light welterweight	140	63.5
Welterweight	–	147	66.7
Super welterweight	Junior middleweight, light middleweight	154	69.9
Middleweight	–	160	72.6
Super middleweight	–	168	76.2
Light heavyweight	–	175	79.4
Cruiserweight	Junior heavyweight	200	90.7
Bridgerweight (WBC only)	–	224	101.6
Heavyweight	–	over 200 (WBC: over 224)	over 90.7

Read the gaps, not just the numbers. At the bottom the divisions are three or four pounds apart, because at 50 kg a kilogram is two per cent of a boxer; from welterweight up the steps are seven and eight pounds, then twenty-five, then infinity. A 91 kg cruiserweight and a 120 kg heavyweight are neighbours on paper and in different sports in the ring. The limits are in pounds because the men who wrote them were English and American; the kilogram column is a rounded conversion, and a lightweight at 61.3 kg is over.

Where the original eight came from

The prize ring had one weight class and called it boxing: the champion was the heaviest man standing, and the Queensberry rules of 1867 said nothing about weight. Order came from clubs and legislatures. By 1909 the National Sporting Club in London had fixed eight classes with limits, and New York's Walker Law of 1920 wrote essentially the same eight into American law – flyweight, bantamweight, featherweight, lightweight, welterweight, middleweight, light heavyweight and heavyweight.

Light heavyweight was the newest of them, invented in Chicago in 1903 by a manager called Lou Houseman for his fighter Jack Root, too big for the middleweights and too small for the heavyweights. The junior classes were New York inventions of the 1920s, and the rest arrived as the sanctioning bodies multiplied: cruiserweight in 1979, super middleweight in 1984, minimumweight in 1987. By 1990 there were seventeen, and there they stayed for thirty years until a boy in Wyoming met a dog. The longer story is in Boxing: From Bare Knuckles to the Queensberry Rules.

Junior, super, light: three names for the same limit

The in-between classes never had a single name, because each was created by somebody with a belt to sell. The WBC and the WBA say super, attached to the class below: super featherweight is 130 lb. The IBF and the WBO say junior, attached to the class above: junior lightweight is the same 130 lb. British boxing and the amateurs long said light for two of them – light welterweight for 140, light middleweight for 154 – and the 105 lb class is minimumweight, mini flyweight or strawweight depending on which belt is on the table. The number is the only thing that never moves: a boxer holding the WBC super lightweight and the IBF junior welterweight titles is a unified champion at 140 lb, not a man who has won two divisions.

Weigh-in day, and the day after

Until the 1980s professionals weighed in on the morning of the fight. Commissions moved it to the day before on safety grounds, so that a boxer who had starved to make the limit had a night to recover. The unintended consequence is the modern weight cut. A boxer who weighs 66.7 kg at two o'clock on Friday can weigh 75 on Saturday night, and at the top of the sport a rehydration of 5 to 10 kg is normal rather than remarkable. Two welterweights are, by the first bell, two middleweights who happen to have been very thirsty.

The IBF answers with a second weigh-in on the morning of its title fights, capped at 10 lb over the limit except at heavyweight; most bodies look the other way. The amateurs never had the problem, because the IBA and its predecessors weigh boxers on the morning of each bout, so the weight you make is roughly the weight you fight at. That single difference decides how much cutting is sensible: Weight Cut Basics has the numbers and The Last Week Before Competition the timetable.

The Olympic classes, as of 2026

Amateur boxing counts in kilograms and rewrites its divisions every few years, so treat this table as dated to 2026. At Paris 2024 there were thirteen classes.

Men, Paris 2024 (kg)	Women, Paris 2024 (kg)
51	50
57	54
63.5	57
71	60
80	66
92	–
over 92	–

Los Angeles 2028 will be run by World Boxing, recognised by the IOC in 2025, with seven classes for men and seven for women; the limits were not finally settled when this was written. The IBA's own championships continue in parallel with a larger ladder: thirteen classes for elite men from 48 kg to over 92 kg, twelve for elite women from 48 kg to over 81 kg. Ask your federation which ladder it uses before you pick a target weight.

Muay Thai and kickboxing borrow the ladder

Walk into Rajadamnern or Lumpinee Stadium in Bangkok and the weights on the card are boxing's, in pounds and with boxing's names, from mini flyweight at 105 lb to welterweight at 147. The Thai stadiums adopted the Western system in the twentieth century, and because most Thai fighters are small the action lives between 105 and 135 lb. The history of Muay Thai covers that borrowing; the point here is that a Thai lightweight and a boxing lightweight are the same 61.2 kg.

The amateur side, run by IFMA, uses kilogram classes closer to the Olympic pattern, and kickboxing promotions have gone metric too: Glory's featherweight is 65 kg, its lightweight 70, its welterweight 77. If you cross between the sports, check the number, not the name. A kickboxing welterweight is ten kilograms heavier than a boxing one.

How to pick your class

Weigh yourself every morning for a week and take the average. That is your walking weight, and for a first amateur fight your class is the one that number falls into, or the one below it if you are within a kilogram or two of the line. A novice who arrives at a same-day weigh-in drained has thrown away the only advantage he had, which was being fresh.

Move down only when you have a dozen bouts, you are carrying fat rather than muscle, and a coach who has watched you spar agrees. Move up when you are cutting more than a few per cent and losing the third round for it. The best fighters in every era found the class where they were the big, strong one at the weigh-in and still had legs at the end, which is a question of honesty before it is a question of nutrition.

Sources

• World Boxing Council. WBC Rules and Regulations (current edition); bridgerweight announcement, 2020.
• WBA, IBF and WBO. Rules and championship ratings (current editions).
• International Boxing Association. IBA Technical and Competition Rules (current edition).
• International Olympic Committee. Paris 2024 Boxing – Competition Format and Weight Categories.
• International Federation of Muaythai Associations. IFMA Rules and Regulations (current edition).
• Wikipedia. “Weight class (boxing)”; “Boxing at the 2024 Summer Olympics.”

Where to go next

• What the judges do with those seventeen divisions: How Boxing Is Scored.
• Same-day weigh-ins and twelve rounds are only the start: Amateur vs Professional Boxing.
• The cage has fewer classes and its own weigh-in culture: Boxing vs MMA.
• The one punch that works at every weight: The Jab: Five Most Common Mistakes.
• The boxing hub for everything else.