Atomweight

Last updated: June 30, 2026

What is atomweight in MMA?

Atomweight is the smallest weight class recognised across professional MMA. The cap sits at roughly 105 pounds in most promotions, which places it directly below strawweight and at the bottom of the sport’s weight ladder. According to Wikipedia’s record of the division, it is used almost exclusively for women’s fights.

The class does not appear in the Unified Rules of Mixed Martial Arts, the framework most North American athletic commissions follow. That is why the exact limit shifts from one organisation to the next instead of being fixed by a single governing body. What stays constant is the purpose: atomweight gives the smallest female fighters a division where they face opponents of a similar build rather than cutting drastically or moving up to meet larger women.

You will mostly hear the term in promotions built around lighter athletes. ONE Championship and Invicta FC are the best known, alongside Japanese organisations such as Rizin and Deep Jewels. The UFC does not run the division. That absence is the single biggest reason casual fans rarely encounter the class.

Atomweight weight limit by promotion

Because no central rulebook defines atomweight, each promotion sets its own ceiling. Most land at or near 105 pounds, but ONE Championship is the notable outlier.

Promotion	Atomweight upper limit
Invicta FC	105 lb (47.6 kg)
Deep Jewels	105 lb (47.6 kg)
Pancrase	47.6 kg (105 lb)
Shooto	47.6 kg (105 lb)
Road FC	48 kg (105.8 lb)
ONE Championship	115 lb (52.2 kg)

ONE’s number looks high because the promotion measures fighters differently. Following a fighter’s death linked to dehydration in 2015, ONE moved to a system based on a competitor’s natural walking weight and added hydration testing, so its atomweight ceiling reads closer to what other groups would call strawweight. Rizin, meanwhile, runs a heavier “super atomweight” bracket at around 49 kg (108 lb) alongside the standard class.

Atomweight vs. strawweight

This is where most of the confusion starts. Atomweight and strawweight sit next to each other, and the names get swapped constantly, but they are separate divisions roughly ten pounds apart.

	Atomweight	Strawweight
Upper limit	~105 lb (47.6 kg)	115 lb (52.2 kg)
Position	Lightest class in MMA	One step above atomweight
In the UFC?	No	Yes (lightest women’s division)
Common promotions	ONE, Invicta, Rizin, Deep Jewels	UFC, ONE, Invicta, PFL

Strawweight is the lighter end of the UFC’s women’s roster and the division most fans know by name. Atomweight sits one rung lower and lives mainly outside the UFC. A fighter who struggles to make 105 will often campaign at strawweight instead, and several atomweight champions have moved up to chase bigger contracts.

Why the UFC has no atomweight division

The UFC’s lightest women’s class is strawweight at 115 pounds, so anyone under that threshold has no dedicated home in the promotion. The talent pool is the usual explanation. Most elite sub-105 fighters compete in Asia, where ONE Championship and Japanese promotions have developed the division for years.

UFC CEO Dana White has acknowledged the idea without committing to it. At a 2020 press conference reported by Fightful, he said he had thought about adding the class but that it was not the year to do it. Speaking on the Contender Series in 2024, per Vendetta Sports Media, White suggested that growing talent in South America and Asia could eventually push the promotion to create another division. For now, it stays a possibility rather than a plan.

Notable atomweight fighters

A handful of names give the division its profile. Angela Lee won ONE Championship’s inaugural women’s atomweight world title in 2016 and, according to ONE, became the youngest MMA world champion in history at 19. Japan’s Seika Izawa has built a reputation as one of the division’s standout talents while staying undefeated through her professional career. Ayaka Hamasaki, a longtime veteran of women’s MMA, has held atomweight gold in both Invicta FC and Rizin.

Frequently Asked Questions

Is atomweight only for women?

In practice, yes. Wikipedia notes the division is used almost exclusively for women’s MMA, and no major promotion runs a men’s atomweight class.

What is the lightest weight class in MMA?

Atomweight, at roughly 105 pounds. Nothing below it is widely recognised in professional MMA.

Is atomweight in the UFC?

No. The UFC’s lightest women’s division is strawweight at 115 pounds. Atomweight is found in promotions such as ONE Championship and Invicta FC.

How much does an atomweight fighter weigh?

At or below the promotion’s limit on fight night, usually 105 pounds, though ONE Championship allows up to 115 pounds under its walking-weight system.

What was atomweight called before?

Japan’s Deep Jewels promotion ran the class as featherweight until renaming it atomweight in May 2015, according to Wikipedia.

---

Sources

1. Wikipedia. “Atomweight (MMA).” Accessed June 2026.
   https://en.wikipedia.org/wiki/Atomweight_(MMA)
2. Wikipedia. “Mixed martial arts weight classes.” Accessed June 2026.
   https://en.wikipedia.org/wiki/Mixed_martial_arts_weight_classes
3. ONE Championship. “A Complete History Of The ONE Women’s Atomweight MMA World Championship.” Accessed June 2026.
   https://www.onefc.com/features/a-complete-history-of-the-one-womens-atomweight-mma-world-championship/
4. Fightful. “Dana White Has ‘Definitely Thought About’ A UFC Women’s Atomweight Division.” Accessed June 2026.
   https://www.fightful.com/mma/dana-white-has-definitely-thought-about-ufc-women-s-atomweight-division/
5. Vendetta Sports Media. “Dana White Expresses Interest In Adding UFC Women’s Atomweight Division.” Accessed June 2026.
   https://vendettasportsmedia.com/dana-white-expresses-interest-adding-ufc-womens-atomweight-division/

Related MMA Terms