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Muay Thai Weight Classes (kg & lb): Full 2026 Chart
By Simon Jounan · Founder of MyFightPrep · Kickboxer & Muay Thai fighter
Published · 8 min read
Contents
Muay Thai has no single set of weight classes: amateurs compete in IFMA’s metric classes (for example -63.5 kg, -67 kg, -71 kg), professionals under WBC Muaythai use boxing-style pound limits (135 lb, 147 lb, 154 lb and so on), and ONE Championship runs its own ten classes with a mandatory hydration test. Below are the full, current tables for each in kg and lb, plus how weigh-ins work and how to choose a class you can make without wrecking your fight.
Limits checked: September 2026 — confirm with your event’s current rulebook.
Who sets the weight classes in Muay Thai?
Your weight class depends on who sanctions the fight. There are three main systems you’ll meet:
- IFMA (International Federation of Muaythai Associations) governs amateur Muay Thai worldwide — national championships, the IFMA Worlds and multi-sport games. IFMA received full IOC recognition in 2021 (IFMA, 2021).
- WBC Muaythai sanctions professional title fights and publishes a pound-based division ladder that many pro shows mirror.
- ONE Championship is the largest pro promotion running Muay Thai, and it uses its own classes for Muay Thai, kickboxing and MMA alike.
Local promotions and interclub shows often set a contracted weight instead of a formal class. Always check the bout sheet, not just the class name.
IFMA weight classes (amateur Muay Thai)
IFMA uses kilograms only. The table below is the Elite (and Masters) division from the IFMA Rules & Regulations v3.057, revised 11 May 2026 (IFMA, 2026). Elite athletes are 18–40 years old, and the U24 division uses the same ladder.
| Limit (kg) | Limit (lb) | Men | Women |
|---|---|---|---|
| 45 kg | 99.2 lb | Multi-sport events only | Yes |
| 48 kg | 105.8 lb | Yes | Yes |
| 51 kg | 112.4 lb | Yes | Yes |
| 54 kg | 119.0 lb | Yes | Yes |
| 57 kg | 125.7 lb | Yes | Yes |
| 60 kg | 132.3 lb | Yes | Yes |
| 63.5 kg | 140.0 lb | Yes | Yes |
| 67 kg | 147.7 lb | Yes | Yes |
| 71 kg | 156.5 lb | Yes | Yes |
| 75 kg | 165.3 lb | Yes | Yes |
| Over 75 kg | Over 165.3 lb | — | Yes (+75 kg) |
| 81 kg | 178.6 lb | Yes | — |
| 86 kg | 189.6 lb | Yes | — |
| 91 kg | 200.6 lb | Yes | — |
| Over 91 kg | Over 200.6 lb | Yes (+91 kg) | — |
The men’s 45 kg class is used only at selected multi-sport events with IFMA Executive Committee approval. Youth categories (U18 down to U8) have their own, lighter ladders in the same document.
WBC Muaythai weight classes (professional)
WBC Muaythai sets limits in pounds, with kilograms stated alongside. These are the divisions in Rule 5 of its Championship Rules & Regulations (WBC Muaythai, 2026).
| Division | Limit (lb) | Limit (kg) |
|---|---|---|
| Minimumweight (women only) | 100 lb | 45.4 kg |
| Mini-flyweight | 105 lb | 47.6 kg |
| Light flyweight | 108 lb | 49.0 kg |
| Flyweight | 112 lb | 50.8 kg |
| Super flyweight | 115 lb | 52.2 kg |
| Bantamweight | 118 lb | 53.5 kg |
| Super bantamweight | 122 lb | 55.3 kg |
| Featherweight | 126 lb | 57.2 kg |
| Super featherweight | 130 lb | 59.0 kg |
| Lightweight | 135 lb | 61.2 kg |
| Super lightweight | 140 lb | 63.5 kg |
| Welterweight | 147 lb | 66.7 kg |
| Super welterweight | 154 lb | 69.9 kg |
| Middleweight | 160 lb | 72.6 kg |
| Super middleweight | 168 lb | 76.2 kg |
| Light heavyweight | 175 lb | 79.4 kg |
| Cruiserweight | 200 lb | 90.7 kg |
| Heavyweight | over 200 lb | over 90.7 kg |
In the US, the Association of Boxing Commissions’ Unified Rules of Professional Muay Thai recommend the same ladder from 105 lb up to cruiserweight at 200 lb, then add heavyweight up to 225 lb and super heavyweight above that (ABC, 2024).
ONE Championship Muay Thai weight classes
ONE uses one table for all its sports, and every limit has to be made while you are hydrated (ONE Championship, 2026).
| Class | Over | Up to |
|---|---|---|
| Atomweight | 105 lb (47.6 kg) | 115 lb (52.2 kg) |
| Strawweight | 115 lb (52.2 kg) | 125 lb (56.7 kg) |
| Flyweight | 125 lb (56.7 kg) | 135 lb (61.2 kg) |
| Bantamweight | 135 lb (61.2 kg) | 145 lb (65.8 kg) |
| Featherweight | 145 lb (65.8 kg) | 155 lb (70.3 kg) |
| Lightweight | 155 lb (70.3 kg) | 170 lb (77.1 kg) |
| Welterweight | 170 lb (77.1 kg) | 185 lb (83.9 kg) |
| Middleweight | 185 lb (83.9 kg) | 205 lb (93.0 kg) |
| Light heavyweight | 205 lb (93.0 kg) | 225 lb (102.1 kg) |
| Heavyweight | 225 lb (102.1 kg) | 265 lb (120.2 kg) |
Notice that ONE’s names don’t match other organisations: a ONE “flyweight” (up to 135 lb) is about the same weight as a WBC lightweight. The limits are also higher than they look, because ONE doesn’t let you dehydrate down to them (see weigh-ins below).
How Muay Thai weigh-ins work
The timing of the weigh-in matters as much as the number, because it decides how long you have to recover. Each system does it differently:
| IFMA (amateur) | WBC Muaythai (pro) | ONE Championship | |
|---|---|---|---|
| When | Morning of each competition day | 24–30 hours before the bout | 24–48 hours before the event |
| Recovery before fighting | Usually at least 3 hours | About a day | About a day or more |
| Extra checks | Only one attempt per day; a pre-contest weigh-in can disqualify you at 5% over your class | Safety weigh-ins at 30, 14 and 7 days out | Urine specific gravity must be ≤1.025 |
| If you miss | One attempt only; the recorded weight is final | Title bouts can go ahead only if you’re no more than 2.2 kg (5 lb) over, and you can’t win the title | You can retry within a 3-hour window; otherwise a catchweight may be negotiated |
A few details matter here:
- IFMA weighs you in light underwear, “fully prepared” for competition, and you only get one attempt per day. The recorded weight is final (IFMA, 2026). Because you weigh in on every fight day of a tournament, you can’t dehydrate hard for day one and rehydrate freely.
- WBC Muaythai expects you to be within 10% of the limit 30 days out, 5% at 14 days and 3% at 7 days (WBC Muaythai, 2026). That is a built-in check on huge cuts.
- ONE uses a refractometer on a supervised urine sample. If you fail the hydration test, you can’t step on the scale until you pass (ONE Championship, 2026). In practice, your walking weight has to sit much closer to the limit.
The International Society of Sports Nutrition classes amateur Muay Thai as a 4–12-hour weigh-in-to-fight sport, and professional Muay Thai as 24–36 hours (Ricci et al., 2025). The shorter the window, the less water weight you can safely cut. See our guide to rehydrating after the weigh-in for the recovery side.
Amateur vs pro: what else changes
Amateur and pro Muay Thai differ in more than their weight tables. Format and equipment change, and many national bodies also grade fighters by experience level on top of weight class.
In Ontario’s amateur rules, for example, C-class bans knees and elbows to the head, B-class bans knees and 12-to-6 elbows to the head, and A-class allows all legal Muay Thai techniques (Government of Ontario, 2025). Letter classes and their exact rules vary by country, so ask your national federation.
Where do common weights land?
This quick converter answers the most-searched questions. Each weight is treated as your weigh-in number, not your walking weight.
| Weigh-in weight | IFMA | WBC Muaythai | ONE |
|---|---|---|---|
| 57 kg / 125.7 lb | -57 kg | Featherweight (126 lb) | Flyweight |
| 63.5 kg / 140 lb | -63.5 kg | Super lightweight (140 lb) | Bantamweight |
| 70 kg / 154.3 lb | -71 kg | Middleweight (over 154 lb) | Featherweight |
| 77.1 kg / 170 lb | -81 kg | Light heavyweight (175 lb) | Lightweight (at the limit) |
| 85 kg / 187.4 lb | -86 kg | Cruiserweight (200 lb) | Middleweight |
How to choose your Muay Thai weight class
Pick the class you can make with a small, planned cut and still fight at your best, not the lowest number you can survive. A good process looks like this:
- Start from your lean training weight. Weigh yourself every morning for two weeks under the same conditions and use the average, not your best day.
- Check the gap. The ISSN position stand notes that combat athletes are commonly advised to lose about 0.5–1 kg of body mass per week during camp. It puts the “optimal” acute water cut at around 2–4% of body mass within 24 hours of weigh-in, with appropriate supervision (Ricci et al., 2025). If reaching a class needs more than that, move up.
- Match the cut to the weigh-in. A same-day IFMA weigh-in leaves you no room for a big water cut. A day-before pro weigh-in gives you more room, but not unlimited room. Under ONE’s hydration rules there is essentially no water cut at all.
- Base the class on body composition, not hope. The ACSM consensus statement recommends setting a minimum competition weight from pre-season body composition and banning unhealthy weight-loss methods (Burke et al., 2021).
- For your first fights, go up if in doubt. Being a little smaller than your opponent costs far less than walking to the ring drained.
Want your own numbers? The weight cut calculator shows the weekly pace you’d need and what’s left for fight week.
For the actual numbers, read how much weight you can safely cut and our step-by-step guide to cutting weight for a fight. If you cross-train, compare these tables with kickboxing weight classes and MMA weight classes in kg, or see the overview of combat sports weight classes.
MyFightPrep tracks your weight trend toward the class limit and fight date, so you know early whether a class is realistic — free.
Important
This guide is general information, not medical advice. Weight classes and weigh-in rules change, so always confirm the limits in your event’s current rulebook or bout agreement. Rapid dehydration can be dangerous. Never use diuretics, laxatives, vomiting or heavy sweat suits to make weight. Stop and get help if you feel dizzy, confused, faint or develop cramps. Young fighters and beginners should cut little or no water weight and should plan their class with a coach and a doctor.
Frequently asked questions
What are the weight classes in Muay Thai?
It depends on the organisation. Amateur Muay Thai under IFMA uses 13 main men's classes from 48 kg to over 91 kg and 11 women's classes from 45 kg to over 75 kg. Pro WBC Muaythai uses boxing-style pound limits from 100 lb to over 200 lb, and ONE Championship uses 10 classes from atomweight (115 lb) to heavyweight (265 lb).
What weight class is 170 pounds in Muay Thai?
170 lb is 77.1 kg. That puts you in IFMA's -81 kg class, WBC Muaythai's light heavyweight (over 168 up to 175 lb), and ONE Championship's lightweight, whose upper limit is exactly 170 lb and must be made while passing a hydration test.
What weight class is 70 kg in Muay Thai?
70 kg (154.3 lb) fits IFMA's -71 kg class. Under WBC Muaythai it is just over the 154 lb super welterweight limit (69.85 kg), so you would need to be slightly lighter for that class or compete at middleweight (160 lb). In ONE it falls in featherweight (145–155 lb).
How do Muay Thai weigh-ins work?
Amateur IFMA events weigh you in the morning of every competition day, with fights starting no earlier than three hours later. Pro WBC Muaythai fights use an official weigh-in 24–30 hours before the bout, while ONE Championship requires you to pass a urine hydration test as well as make weight.
Is Muay Thai an Olympic sport?
Not yet. IFMA, the amateur world federation, received full IOC recognition in 2021, but Muaythai is not currently on the Olympic programme.
Sources
This guide is based on the works below. Numbers in the text refer to them.
- International Federation of Muaythai Associations (IFMA) (2026). IFMA Muaythai Rules & Regulations (v3.057, revised 11 May 2026)
- International Federation of Muaythai Associations (IFMA) (2021). Muaythai & IFMA receives official confirmation on IOC recognition
- WBC Muaythai (2026). WBC Muaythai Championship Rules & Regulations — Rule 5: Weight Divisions and Weigh-In
- ONE Championship (2026). ONE Championship Martial Arts: Weight Classes and Hydration Testing
- Association of Boxing Commissions and Combative Sports (ABC) (2024). Unified Rules of Professional Muay Thai (approved July 2024)
- Government of Ontario (2025). Amateur Combative Sport Rules: Muay Thai – Ring Sport Disciplines, Part IV: Competition Requirements
- Ricci AA, Evans C, Stull C, et al. (2025). International Society of Sports Nutrition Position Stand: Nutrition and Weight Cut Strategies for Mixed Martial Arts and Other Combat Sports
- Burke LM, Slater GJ, Matthews JJ, Langan-Evans C, Horswill CA (2021). ACSM Expert Consensus Statement on Weight Loss in Weight-Category Sports