This guide explains the UMB World Rules, edition 1 January 1989. The linked competition regulations determine current distances, clocks and exceptions; this summary is not the full rulebook.
What makes a three-cushion point legal?
Cushion contacts before or after the first object ball may count. The same cushion may be contacted more than once; three different cushions are not required.
The valid carom
For the player at the table, the cue ball is distinct from the two object balls: the opponent’s cue ball and the red. Your own cue ball is not a third object ball.
A valid three-cushion carom requires that, after you strike your cue ball, it:
- contacts both object balls, and
- touches at least three cushions before it reaches the second object ball.
The order is otherwise free: cushion contacts and the first object-ball contact may happen in any sequence, as long as the cue ball completes at least three cushion contacts before touching the second object ball. Repeated contact with the same cushion counts each time.
Scoring & innings
- Each valid carom scores 1 point.
- A player continues at the table as long as they keep scoring. A miss ends the turn — one turn is an inning.
- A player's average is points ÷ innings; interpret it in the context of the event, distance and player level.
The opening break
The lag winner chooses who starts. The referee places the red on the top spot and the opponent’s cue ball on the bottom spot; the starting player chooses one of the two starting spots for their cue ball. The first object ball contacted on the opening shot must be the red. UMB · 23 · 1989
Fouls
A miss or foul ends the turn without a point. Ball positions are not always left unchanged: in three-cushion, balls that leave the table are re-spotted under Articles 27–28. Only the affected balls are replaced, not automatically all three in the opening layout. Common fouls: UMB · 27–28 · 1989
- The cue ball or any ball leaving the table.
- Touching a ball with anything other than the cue tip.
- Double hit or push shot (tip stays on the cue ball).
- Shooting before all balls have stopped, or out of turn.
- Not having at least one foot on the floor.
- Time foul — exceeding the shot clock.
Match format
The event edition determines distance, shot clock, time extensions and whether an equalizing inning exists. Article 29 allows formats with or without equal innings; never assume a rule from one stage or tournament applies to another. Check the organiser’s regulations before the match.
Equipment rules
The international playing surface is 2.84 × 1.42 m between cushion noses (±5 mm); tournament tables are heated. Regulation balls are 61–61.5 mm and 205–220 g, with no more than 2 g difference in the set. These are physical rules, not a claim that every club table or simulation uses identical equipment.
Other carom games
- Libre (free game): no cushion requirement — simply carom off both object balls. Restricted "balk" zones (corner boxes) stop endless nursing.
- Balkline (47/2, 71/2): the table is divided by lines; only a limited number of shots is allowed with both object balls inside a balk space.
- One-cushion: at least one cushion before the second object ball.
- Artistic billiards: a fixed program of set trick shots scored by difficulty.
Practise the rules free in 3ball
3ball displays simulated contacts and whether they meet its selected game condition. Replay a position to study the sequence, then compare on a real table. A model is not a tournament referee and does not reproduce every foul, table condition or event format.