MMA Rules Explained: What Is Legal, What Is Illegal, How Fights Are Judged

The fighter on the bottom flattens one hand on the canvas, and the man standing over him with a knee already loaded has about a quarter of a second to decide. One hand down: the knee to the head is legal. Two hands down: it is a foul, a point, possibly the whole fight. Everyone in the cage knows this. Most of the people in the seats do not, which is why the loudest noise at an MMA event is usually a crowd booing something that was entirely within the rules.

The short answer: professional MMA in most of the world runs on one document, the Unified Rules of Mixed Martial Arts, and it is shorter than you think. Five-minute rounds, four-ounce gloves, a fenced area, five ways to win, three judges scoring rounds by a fixed order of criteria, and a list of fouls that fits on a page. I will take you through all of it, then through the places where ONE Championship, the old PRIDE rules and the amateur game go their own way.

Key facts

Rule book

Unified Rules of MMA – New Jersey 2000, ABC 2009, revised 2017

Rounds

3 × 5 minutes; 5 × 5 for title fights; one-minute break

Gloves

4 oz minimum, 6 oz maximum; the UFC uses 4 oz

Ways to win

Knockout, TKO, submission, decision, disqualification

Scoring

10-point must, three judges, criteria in strict order

Fouls

Around thirty listed, from eye gouging to timidity

Where the rules came from

In 2000 the sport had been thrown off pay-per-view, banned in most American states and called human cockfighting by a United States senator. The New Jersey State Athletic Control Board wrote down a set of rules that year that gave a regulator something it could regulate: weight classes, timed rounds, gloves, fouls, a doctor at ringside. The UFC fought under them for the first time at UFC 28 in Atlantic City in November 2000, Nevada followed in 2001, and in 2009 the ABC made them the standard for North America. A revision in force from 1 January 2017 rewrote the judging criteria and the grounded definition; that is the version described here. But the Unified Rules are a template, not a law. Each commission adopts its own copy, and some never took the 2017 changes. So when a commentator says “that is illegal”, the honest follow-up is: where?

The shape of a fight

Rounds are five minutes with one minute between them: three rounds for a normal professional fight, five for a championship, and the UFC has used five for every main event since 2011. Gloves weigh at least 4 oz (113 g) and at most 6 oz; the UFC uses 4. They exist so that fighters can grip, not so that punches hurt less, and next to a boxing glove they look like something you would garden in. The fighting area is a fenced enclosure between 20 and 32 feet (6.1–9.75 m) across, or a ring, which the rules also allow; the UFC’s octagon is 30 feet (9.1 m) between the fence walls. Approved shorts, a mouthpiece, a groin protector for men, hands wrapped under an inspector’s eye. That is the whole kit.

Five ways to win

Result	What it means	Who decides
Knockout	A legal strike leaves a fighter unconscious or unable to continue	Referee
Technical knockout	The referee stops it (no intelligent defence), the doctor stops it, the corner stops it, or the fighter quits	Referee, doctor or corner
Submission	A tap, a verbal tap, or a fighter goes out in a choke (technical submission)	Referee
Decision	Three scorecards: unanimous, split or majority; draws are possible	Judges
Disqualification	An intentional foul ends the fight, or fouls continue after deductions	Referee

Two results sit outside the table: a no contest, when an accidental foul ends a fight early, and a technical decision, when the same accident happens late enough for the scorecards to settle it. Both come back under the referee’s tools.

How the judges see it

MMA borrowed boxing’s 10-point must system: the round winner gets 10, the loser 9 or fewer, each round on its own with no carry-over. What differs from boxing is the order of the criteria, and since 2017 that order is strict. First, effective striking and grappling: strikes that land with impact, takedowns that lead somewhere, submissions that threaten. Only if those are equal does effective aggressiveness count, meaning the fighter pushing to finish rather than merely walking forward. Only if both are equal does fighting-area control count. “Octagon control” is the criterion every losing corner cites and the one the rules rank last.

A 10–8 is for a round won by a large margin, and the criteria name three things to look for: impact, dominance and duration. One of them, taken to an extreme, is enough. A 10–7 is for a fighter overwhelmed to the point where the referee nearly stepped in; a 10–10 is discouraged and almost never given. Three cards agreeing is a unanimous decision, two against one a split, two for one fighter and a draw on the third a majority. The boxing version of the same arithmetic is in How Boxing Is Scored.

What you cannot do

Foul	Note
Head butts, biting, spitting, hair pulling, fish-hooking	Obvious
Eye gouging; fingers extended towards the face	Extended fingers were added in 2017 against eye pokes
Groin attacks	Up to five minutes to recover
Fingers in any orifice or cut	Reopening a cut by hand is not a technique
Small-joint manipulation	Single fingers and toes; four together are fine
Strikes to the spine or back of the head	The crown and the strip to the nape, the Mohawk in referee training
12-to-6 elbows	Straight down with the point; Jon Jones’s only defeat, in 2009, was a disqualification for this
Throat strikes; clawing, pinching, twisting flesh; grabbing the clavicle	Fighting, not gripping the person
Kicks or knees to the head of a grounded opponent; stomps	See below
Spiking on the head or neck; throwing an opponent out of the cage	A slam may not land him on his head
Holding the fence, shorts or gloves	Fingers in the mesh to stop a takedown is the usual case
Attacking during a break, after the bell or under the referee’s care	Instant deduction territory
Timidity	Avoiding contact, dropping the mouthpiece on purpose, faking an injury
Disregard of the referee; abusive language; corner interference	Conduct fouls

The grounded rule gets its own paragraph because it changed in 2017 and the change was not adopted everywhere. Under the old wording one hand on the floor made you grounded and safe from knees and kicks to the head, and fighters learned to touch the canvas with a fingertip the moment a knee was coming: a clever use of the rules and a strange way to fight. Since 2017 a single hand no longer counts. To be grounded you need both hands down, palm or fist, or any other body part on the floor, a knee, a hip, the back. Some commissions took the new wording, some did not, and the UFC fights under whichever applies in the building it is in.

The referee’s toolbox

The referee has three instruments: a verbal warning, a point deduction and a disqualification. Only the referee can take a point, and it comes off that round’s score, so a 10–9 becomes 9–9. The referee can also stop the clock, call in the doctor and give a fouled fighter time to recover: up to five minutes after a low blow, and at the referee’s discretion after an eye poke, with the doctor deciding whether the eye can see.

If a foul ends the fight, intent and timing decide the result. An intentional foul that leaves the opponent unable to continue is a disqualification. An accidental one, a clash of heads or a stray finger, is a no contest before the halfway point (the end of round two of three, or three of five) and a technical decision on the scorecards after it. The ringside physician can stop a fight at any time, and the referee cannot overrule the doctor. Judges never stop a fight; they only score it.

Weigh-ins and the 24-hour rule

The Unified Rules leave the weigh-in to the commission, and the practice almost everywhere is the day before, roughly 24 to 36 hours before the walk; the UFC has held its official weigh-in early in the morning since 2016, with a staged one later for the cameras. That gap is why fighters cut weight. The divisions and the one-pound allowance are in MMA Weight Classes Explained, the cut itself in Weight Cut Basics, and what to drink between the scale and the bell in Hydration on Fight Day.

Same sport, different rule books

PRIDE ran in Japan from 1997 to 2007 in a ring, with a ten-minute first round followed by two of five. Soccer kicks, stomps and knees to the head of a grounded opponent were legal; elbows to the head were not. Judges scored the whole fight rather than rounds, with the effort to finish ranked first, and a yellow card for stalling cost a fighter a tenth of his purse.

ONE Championship, based in Singapore since 2011, kept some of that. Its Global Martial Arts Rule Set allows knees to the head of a grounded opponent but bans kicks and stomps to it, and its judges score the bout as a whole, weighing near-finishes, damage, striking and grappling, takedowns and aggression in that order. It also abolished weight cutting, a story for the weight-class guide.

Amateur MMA is stricter, not looser. IMMAF, the international amateur federation, uses three rounds of three minutes, heavier gloves and shin protection, and bans elbows to the head; several national amateur rule sets also ban knees to the head. The rules you have watched on television are not the ones you will fight under at your first amateur show. The ones that count are the ones your commission signed, and reading them beats arguing with the referee.

Sources

• Unified Rules of Mixed Martial Arts, Association of Boxing Commissions and Combative Sports (abcboxing.com)
• Rules and Regulations: Unified Rules of Mixed Martial Arts, UFC (ufc.com)
• Unified Rules of Amateur Mixed Martial Arts, International Mixed Martial Arts Federation (immaf.org)
• Global Martial Arts Rule Set, ONE Championship (onefc.com)
• “Mixed martial arts rules”, Wikipedia

Where to go next

• The divisions, the allowance and what happens when someone misses weight: MMA Weight Classes Explained.
• The same 10-point system in the sport that invented it: How Boxing Is Scored.
• How the rules got here: History of MMA.
• What the rules mean for a striker crossing over: Boxing vs MMA, Muay Thai vs MMA and Karate vs MMA.
• The MMA hub.