Eight-ball

The regulation size of the table's playing surface is 9 by 4.5 ft (2.7 by 1.4 m), though exact dimensions may vary slightly by manufacturer. Some leagues and tournaments using the World Standardized Rules may allow smaller sizes, down to 7 by 3.5 ft (2.1 by 1.1 m). Early 20th-century 10 by 5 ft (3.0 by 1.5 m) models are occasionally also still used. WPA professional competition generally employs regulation tables, while the amateur league championships of various leagues, including ACS, BCAPL, VNEA, and APA, use the seven-foot tables in order to fit more of them into the hosting venue.

There are seven solid-colored balls numbered 1 through 7, seven striped balls numbered 9 through 15, an 8 ball, and a cue ball. The balls are usually colored as follows:

• 1 and 9: yellow
• 2 and 10: blue
• 3 and 11: red
• 4 and 12: purple (TV: pink)¹
• 5 and 13: orange
• 6 and 14: green
• 7 and 15: maroon (TV: tan)¹
• 8: black
• Cue: white

¹Special sets designed to be more easily discernible on television substitute a rather light tan shade for the normally darker brown of the 7 and 15 balls, and pink for the dark purple of the 4 and 12; these alternative-color sets are now also available to consumers.

To start the game, the object balls are placed in a triangular rack. The base of the rack is parallel to the end rail (the short end of the pool table) and positioned so the apex ball of the rack is located on the foot spot. The balls in the rack are ideally placed so that they are all in contact with one another; this is accomplished by pressing the balls together toward the apex ball. The order of the balls should be random, with the exceptions of the 8 ball, which must be placed in the center of the rack (i.e., the middle of the third row), and the two back corner balls, one of which must be a stripe and the other a solid. The cue ball is placed anywhere the breaker desires behind the head string.

One person is chosen by some predetermined method (e.g., coin toss, lag, or win or loss of previous game or match) to shoot first, using the cue ball to break the object-ball rack apart. In most leagues it is the breaker's opponent who racks the balls, but in some, players break their own racks. If the breaker fails to make a successful break—usually defined as at least four balls hitting cushions or an object ball being pocketed—then the opponent can opt either to play from the current position or to call for a re-rack and either re-break or have the original breaker repeat the break.

Long-exposure photograph of a break in eight-ball

If the 8 ball is pocketed on the break, then the breaker can choose either to re-spot the 8 ball and play from the current position or to re-rack and re-break; but if the cue ball is also pocketed on the break then the opponent is the one who has the choice: either to re-spot the 8 ball and shoot with ball-in-hand behind the head string, accepting the current position, or to re-break or have the breaker re-break. (For regional amateur variations, such as pocketing the 8 ball on the break resulting in instant win or loss, see "Informal rule variations", below.)

A player (or team) continues to shoot until committing a foul or failing to legally pocket an object ball (whether intentionally or not); thereupon it is the turn of the opposing players. Play alternates in this manner for the remainder of the game. Following a foul, the incoming player has ball-in-hand anywhere on the table, unless the foul occurred on the break shot, as noted previously.[6]

The table is "open" at the start of the game, meaning that either player may shoot at any ball. It remains open until one player legally pockets one or more object balls (excluding the 8) after the break. That player is assigned the group, or suit, of the pocketed ball – 1–7 (solids), or 9–15 (stripes) – and the other suit is assigned to the opponent. Balls pocketed on the break, or as the result of a foul while the table is still open, are not used to assign the suits. If a player pockets balls from both suits on an open table, they may claim either suit as their own.

Once the suits are assigned, they remain fixed throughout the game. If any balls from a player's suit are on the table, the player must hit one of them first on every shot; otherwise a foul is called and the turn ends. After all balls from the suit have been pocketed, the player's target becomes the 8 for the remainder of the game.

Once all of a player's (or team's) group of object balls are pocketed, the player attempts to sink the 8 ball. In order to win the game the player first designates which pocket the 8 ball will be pocketed into and then successfully pockets the 8 ball into that pocket. If the player knocks the 8 ball off the table then the player loses the game. If the player pockets the 8 ball and commits a foul or pockets it into another pocket than the one designated, then the player loses the game. (For regional amateur variations, such as fouling while trying to pocket the 8 ball resulting in instant loss despite not pocketing the 8 ball, see "Informal rule variations", below.) Otherwise (i.e., if the 8 ball is neither pocketed nor knocked off the table) the shooter's turn is simply over, even if a foul occurs. In short, a World Standardized Rules game of eight-ball, like a game of nine-ball, is not over until the "money ball" is no longer on the table. This rule may be unfamiliar to some bar and league (e.g., APA) players, for whom such a foul normally means losing the game. The rule has been increasingly adopted by amateur leagues, including VNEA beginning with the 2008/2009 season, BCAPL, and USAPL.

Any of the following results in a player winning the game:

• The player legally pockets the 8 ball into a designated pocket, after all of that player's object balls have been pocketed
• The opposing player illegally pockets the 8 ball (e.g., before clearing all of that player's object balls, does so on the same shot as the last such object ball, or sinks the 8 ball into a pocket other than the one that was designated, or commits any foul, including scratching the cue ball into a pocket or knocking it off the table, while pocketing the 8 ball)
  • However, if you scratch after sinking your final designated ball (stripe or solid), you do not lose immediately.
• The opposing player knocks the 8 ball off the table

Because of these rules, it's actually possible for a game to end with only one of the players having shot.

• The shooter fails to strike one of their own object balls (or the 8 ball, if all of said object balls are already pocketed) with the cue ball, before other balls (if any) are contacted by the cue ball. This excludes "split" shots, where the cue ball strikes one of the shooter's and one of the opponent's object balls simultaneously.
• No ball comes into contact with a cushion or is pocketed, after legal cue ball contact with the (first) object ball (or 8 ball, if shooting for the 8).
• If an attempt is made to pocket a ball, and the ball hits the pocket, bounces out and lands on the ground, the ball is placed in the pocket and the game continues.
• The shooter does not have at least one foot on the floor (this requirement may be waived if the shooter has a relevant disability, or the venue has not provided a mechanical bridge).
• The cue ball is pocketed.
• The cue ball is shot before all balls have come to a complete stop from the previous shot.
• The cue ball does not strike any ball.
• The cue ball is struck more than once during a shot
• The cue ball is jumped entirely or partially over an obstructing ball with an illegal jump shot that scoops under the cue ball.
• The cue ball is clearly pushed (shoved slowly, rather than struck), with the cue tip remaining in contact with it more than momentarily.
• The shooter touches the cue ball with something other than the tip of the cue.
• The shooter touches any ball (with body, clothing or equipment), other than as necessary to move the cue ball when the player has ball-in-hand.
• The shooter knocks a ball off the table.
• The shooter has shot out-of-turn.
• The shooter has shot the black 8 ball without designating the pocket prior to opposite team members or the match referee, in advance.
• The shooter deliberately pockets the opponents balls while shooting 8-ball.
• On the break shot, no balls are pocketed and fewer than four balls reach the cushions (in which case the incoming player can demand a re-rack and take the break or force the original breaker to re-break, or may take ball-in-hand behind the head string and shoot the balls as they lie)

If these fouls are made, the ball can be placed anywhere on the table to prevent a player from making a purposeful foul to disadvantage the other player.

The British version of eight-ball, known internationally as blackball, has evolved into a separate game, retaining significant elements of the earlier B.B.C. & Co. version of the game, with additional influences from English billiards and snooker. It is popular in amateur competition in Britain, Ireland, Australia, and some other countries.

The game uses unnumbered, solid-colored object balls, typically red and yellow, with one black 8 ball. They are usually 2 inches (51 mm) or 2 ¹⁄₈ inches (54 mm) in diameter, the latter being the same size as the balls used in snooker and English billiards. Tables for blackball pool are 6-to-7-foot (1.8 to 2.1 m) long, and feature pockets with rounded cushion openings, like snooker tables.

The rules of blackball differ from standardized eight-ball in numerous ways, including the handling of fouls, which may give the opponent two shots, racking (the 8 ball, not the apex ball, goes on the spot), selection of which group of balls will be shot by which player, handling of frozen balls and snookers, and many other details.

Internationally, the World Pool-Billiard Association and the World Eightball Pool Federation both publish rules and promote events. The two rule sets differ in some details regarding the penalties for fouls.

The hybrid game eight-ball rotation is a combination of eight-ball and rotation, in which the players must pocket their balls (other than the 8, which remains last) in numerical order. Specifically, the solids player starts by pocketing the 1 ball and ascends to the 7 ball, and the stripes player starts by pocketing the 15 ball and descends to the 9 ball.