3x3 (pronounced 3 on 3, 3 by 3 or 3x3) basketball is a form of the game played three a side on one hoop. It is the largest urban team sport in the world (ESSEC study commissioned by IOC). This basketball game format is currently being promoted and structured by FIBA, the sport's governing body. Its main competition is an annual FIBA 3X3 World Tour, comprising a series of Masters and one Final tournament awarding six-figure prize money in US dollars. The FIBA 3x3 World Cups for men and women are the highest tournaments for national 3x3 teams.
FIBA releases from time-to-time a supplement to its official basketball rules specifically for 3x3. The rules state that regular FIBA rules apply to all situations not specifically addressed in the FIBA 3x3 rules. The current set, both in an abbreviated version and longer format, was published in January 2019.
The current rules depart from regular full-court basketball in the following ways:
- Each team consists of three players and one substitute. Each team must have three players on the court when the game begins.
- The game is played on a half-court with one basket. The official court is 15 metres (49 ft) wide (the same as FIBA's standard for the full-court game) by 11 metres (36 ft) in length (compared to FIBA's standard half-court distance of 14 metres (46 ft). However, the rules specifically state that half of a standard FIBA full court is an acceptable playing area for official competitions.
- The basketball is unique to 3x3, and is used in all competitions, whether men's, women's, or mixed. Its circumference is that of the size 6 basketball (28.5 in, 720 mm) used in the women's full-court game. However, its weight is that of the size 7 standard (22 oz, 620 g) used in the men's full-court game.
- A jump ball is not used to start the game. Instead, a coin toss is held immediately before the game. The winning team can choose to take possession of the ball at the start of the game, or take the first possession of a potential overtime period. In turn, this means that if the game goes into overtime, the first possession goes to the team that started the game on defense.
- There are no jump balls at any time in the game, neither is there an alternating possession rule. In any held-ball situation, the defensive team is granted possession.
- Every successful shot inside the arc is awarded one point, while every successful shot behind the arc is awarded two points.
- The game is a single period of 10 minutes with sudden death at 21 points. The winner is the first team to score 21 or the team with the highest score at the end of the 10 minutes. A tie in regulation leads to an untimed overtime period, which is won by the first team to score two points in overtime. Note that if a game is tied at 20 at the end of regulation, reaching 21 does not end the game.
- Game play starts with the defensive team exchanging the ball with the offensive team behind the arc. This exchange is also used to restart the game from any dead ball situation. If a foul is committed that results in the non-fouling team retaining possession — i.e., a technical or "unsportsmanlike" foul (the latter essentially the same as the "flagrant foul" of North American rule sets) — the non-fouling team will receive the exchange.
- A 12-second shot clock is used.
- If the defense gains possession of the ball within the arc, by a steal, a block or a rebound, the team must move the ball behind the arc before being allowed to take a shot.
- After a made goal or free throw (except for technical or unsportsmanlike fouls and team fouls 10 or more), play restarts with a player from the non-scoring team taking the ball directly under the basket and then dribbling or passing it to a point behind the arc. The defense is not allowed to play for the ball inside the block/charge semi-circle under the basket.
- The only common feature between the substitution procedure in full-court and 3x3 is that it can occur only in a dead-ball situation. In 3x3, a substitute can only enter from behind the end line opposite the basket, and the substitution becomes official once the player leaving the game has made physical contact with the substitute. Unlike the full-court game, no action from referees or table officials is required.
- Each team is allowed one timeout. (The officials may still stop the game in case of player injury or other dangerous situations, as in the standard FIBA rules.)
- Individual personal foul counts are not kept. In other words, players cannot be disqualified on the basis of personal fouls. However, a player who commits two unsportsmanlike fouls is disqualified.
- Fouls during the act of shooting inside the arc are awarded 1 free throw, while fouls during the act of shooting behind the arc are awarded 2 free throws. However, team fouls 7, 8 and 9 are awarded 2 free throws, while team fouls 10 or more are awarded 2 free throws and possession of the ball. The "bonus" rule specifically supersedes the normal rule for fouls in the act of shooting.
- Nonetheless, offensive fouls (if not technical or unsportsmanlike) never result in free throws, regardless of the number of team fouls.