Three-cushion belongs to the carom family, which the Union Mondiale de Billard (UMB) governs as one of the three federations in the World Confederation of Billiards Sports. We could not read the UMB's own site for this page, so the rules here come from the US Billiard Association (USBA) rulebook, revised 6 April 2009 according to the document, along with the WCBS, the European carom federation (CEB), and Wikipedia articles that cite UMB rules.
The table
Carom tables have no pockets. The CEB equipment norms (dated 1 August 2012) give these figures:
| Item | CEB norm |
|---|---|
| Playing surface, international match table | 2.84 m by 1.42 m, plus or minus 5 mm |
| Smaller championship sizes | 2.54 by 1.27 m, 2.30 by 1.15 m, and 2.10 by 1.05 m |
| Cushion height at the front edge | 37 mm, plus or minus 1 mm |
| Table height | 75 to 80 cm |
| Slate thickness | At least 45 mm |
Wikipedia gives 3.0 by 1.5 m (10 ft by 5 ft) as the typical carom table size. That reads as the overall size of the table, while the CEB's 2.84 by 1.42 m is the playing surface, so the two figures are measuring different things. Wikipedia also says international tournament rules call for an electrically heated table, often around 5 degrees C above room temperature, though no exact temperature is required.
The balls
Three balls are used: a white cue ball, a yellow cue ball and a red object ball. Each player shoots their own cue ball for the whole game, and the opponent's cue ball counts as one of the two object balls. Wikipedia notes that the second cue ball used to be white with red or black spots, and that both styles of set are permitted in tournaments.
The CEB norms set ball diameter at 61 to 61.5 mm and weight at 205 to 220 g, with no more than 2 g difference within a set. Wikipedia, citing the 1989 UMB World Rules, gives a typical weight of about 210 g.
The lag and the break
Under the USBA rules, each player shoots a ball from the head string to the foot cushion, and the ball that finishes closer to the head cushion wins. The lag winner chooses who breaks and which cue ball to use for the whole game.
For the break, the opponent's cue ball goes on the head spot, the breaker's cue ball 18.25 cm (7 3/16 in) to the left or right of it, and the red on the foot spot. On the break, the cue ball must hit the red first, directly, or it is a foul. After the break, either object ball may be hit first.
Scoring a point
A shot scores one point when your cue ball contacts both object balls and makes at least three cushion contacts before it reaches the second object ball. The USBA rules make two clarifications:
- Same cushion counts. The three contacts do not have to be on three different cushions. Repeated contacts with one or two cushions count toward the total.
- Kisses count. A kiss shot counts whether it helped or hurt the shot.
You keep shooting until you miss. A foul ends your turn but costs no points.
Frozen balls
When your cue ball is frozen to another ball, the USBA rules let you either play away from it or have the balls spotted: the red on the foot spot, your cue ball on the head spot, and your opponent's ball on the center spot.
Fouls
The USBA lists these fouls, each of which ends the inning:
- Touching a ball
- Shooting with no foot on the floor
- Playing the wrong cue ball
- Shooting while balls are still moving
- A push stroke or double stroke
- Jumping a ball off the table
- Playing an intentional safety that has no chance of scoring
A miscue is not a foul under the USBA rules unless the ferrule or shaft touches the cue ball.
Match length
Three-cushion is played to a set number of points, and the number depends on the event. The sources do not agree on one standard:
| Event | Match format | Source |
|---|---|---|
| UMB World Three-cushion Championship, since 2012 | Single games to 40 points | Wikipedia |
| UMB World Championship, 1994 to 2011 | Best-of-five sets | Wikipedia |
| UMB World Championship, 1960 to 1984 | 60 points | Wikipedia |
| UMB World Championship, 1928 to 1958 and 1985 to 1987 | 50 points | Wikipedia |
| CEB European Championship, 2022-23, group matches | 40 points, equal innings | CEB sport rules |
| CEB European Championship, 2022-23, final round | 50 points, no equal innings | CEB sport rules |
| League play (German Bundesliga) | 50 points described as standard | Wikipedia |
The CEB European Championship rules for 2022-23 also set a 40-second shot clock with a warning at 30 seconds, and give each player two time-outs. The first UMB World Three-cushion Championship was held in Reims, France, in 1928.
Other carom games
Three-cushion is one of several carom games. In straight rail, any stroke where the cue ball contacts both object balls scores. Balkline divides the table into rectangular spaces with lines parallel to the rails, and limits how many points can be scored while the object balls sit in one space; in 18.2 balkline, for example, the lines are 18 in from each rail and two counts are allowed per space. In one-cushion, the cue ball must touch at least one cushion before reaching the second object ball.