Rules of snooker

Snooker table, drawn to scale

Snooker is a cue sport that is played on a baize-covered table with pockets in each of the four corners and in the middle of each of the long side cushions. It is played using a cue and snooker balls: one white cue ball, 15 red balls worth one point each (sometimes played with fewer red balls, commonly 6 or 10), and six balls of different colours: yellow (2 points), green (3), brown (4), blue (5), pink (6), black (7). A player (or team) wins a frame (individual game) of snooker by scoring more points than the opponent(s), using the cue ball to pot the red and coloured balls. A player (or team) wins a match when they have achieved the best-of score from a pre-determined number of frames. The number of frames is always odd so as to prevent a tie or a draw.

The table

Snooker is played on a rectangular snooker table with six pockets, one at each corner and one in the middle of each long side. The table usually has a slate base, covered in green baize. At one end of the table (the baulk end) is the baulk line, which is 29 inches (74 cm) from the baulk cushion (the short cushion at the baulk end). A semicircle of radius 11+1⁄2 inches (29 cm), called the D, is drawn behind this line, centred on the middle of the line. The cushion at the other end of the table is known as the top cushion.

A regulation (full-size) table is 12 ft × 6 ft (3.7 m × 1.8 m); because of the large size of these tables, smaller tables are common in homes, pubs and other places where space is limited. These are often around 6 feet (1.8 m) in length, with all the dimensions and markings scaled down accordingly. The balls used are sometimes also scaled down, and/or reduced in number (in the case of the reds) by omitting the longest row of balls in the rack.

The balls

Pack of reds, not touching the pink

Snooker balls, like the balls for all cue sports, are typically made of phenolic resin, but are smaller than pool balls. Regulation snooker balls (which are specified in metric units) are nominally 52.5 mm (approximately 2+1⁄15 inches) in diameter, though many sets are actually manufactured at 52.4 mm (about 2+1⁄16 in.) No weight for the balls is specified in the rules, only that the weight of any two balls should not differ by more than 0.5g. Some recreational sets (which are usually not measured metrically) are 2+1⁄8 in. (about 54 mm) up to as large as pool balls, at 2+1⁄4 in. (about 57.2 mm); larger ball size requires wider pocket openings. Miniature sets also exist, for half-size home tables. There are fifteen red balls, six "colour" balls (yellow, green, brown, blue, pink, and black), and one white cue ball. Usually none of the balls are numbered, though the six colour balls often are in the US, where they are easily mistaken at first glance for pool balls (the design is similar, but the numbering does not match pool's scheme).

At the beginning of a frame, the balls are set up in the arrangement shown in the illustration. The six colours (a term referring to all balls except the white and the reds) are placed on their own spots. On the baulk line, looking up the table from the baulk end, the green ball is located where the "D" meets the line on the left, the brown ball in the middle of the line, and the yellow ball where the "D" meets the line on the right. This order is often remembered using the mnemonic God Bless You, the first letter of each word being the first letter of the three colours (Green, Brown, Yellow). At the exact centre of the table sits the blue ball. Further up the table is the pink ball, which sits midway between the blue spot and the top cushion, followed by the red balls, arranged in a tightly-packed triangle behind the pink (the apex must be as close as possible to the pink ball without touching it). Finally, the black ball is placed on a spot 32.5 cm (12.8 in) from the top cushion.

Objective

The objective of the game of snooker is to strike the white cue ball with a cue in the direction of other object balls and to pot these object balls in one of the six pockets. This must be done according to the rules of the game, described below. By potting object balls points can be scored. The player who scores most points wins the frame, and the player who wins most frames wins the match.

Match

A match usually consists of a fixed, odd number of frames. A frame begins with setting up the balls as described above. A frame ends when all balls are potted, or when one of the players concedes defeat because he is too far behind in score to equal or beat the score of the other player.

A match ends when one of the players has won the majority of the set number of frames and the other player can therefore not equal this. For example, when a match consists of 19 frames, the match ends when one of the players has reached 10 frames.

Gameplay

Snooker table with all balls at the beginning of a frame

At the beginning of each frame the balls are set up by the referee as explained. This will be followed by a break-off shot, on which the players take turns. At the break-off, the white cue ball can be placed anywhere inside the D, although it is common for players to start by placing the ball on the line, between the brown ball and either the green or yellow ball.

Players take turns in visiting the table. When one player is at the table, the other cannot play. A break is the number of points scored by a player in one single visit to the table. A player's turn and break end when he fails to pot a ball, when he does something against the rules of the game, which is called a foul, or when a frame has ended.

The ball or balls that can be hit first by the white are called the ball(s) "on" for that particular stroke. The ball(s) "on" differ from shot to shot: a red ball, if potted, must be followed by a colour, a potted colour must be followed by a red, and so on until a break ends; if a red is not potted, any red ball remains the ball "on". Only a ball or balls "on" may be potted legally by a player. If a ball not "on" is potted, this is a foul.

If the cue ball is touching another ball which is on or could be on, the referee shall state that the ball is a "touching ball", whereupon the striker must "play away" from the ball without moving it, and—because the touching ball is deemed to be the object ball—without being required to hit another ball. If the object ball moves, it is considered a "push shot" and a foul shall be called. No penalty is incurred for playing away if (1) the ball is on; (2) the ball could be on and the striker nominates such ball; or (3) the ball could be on and the striker nominates, and first hits, another ball that could be on. If the cue ball is touching another ball which could not be on, it isn't called a touching ball, and the striker must play away from it and hit a legally nominated object ball. Where the cue ball is touching several object balls simultaneously, the referee shall state "Touching ball" for each and every such object ball, and indicate to the player which object balls he is referring to. The rules for each individual touching ball then apply simultaneously.

If a ball is potted when a foul is made, depending on the situation, the potted ball will either stay off the table, or be spotted on its initial spot or it will—along with any and all balls that were moved during the foul shot—be repositioned to where it/they lay before the shot. For details on such situations, see Fouls and Miss below.

The game of snooker generally consists of two phases. The first phase is the situation in which there are still red balls on the table. In the first phase, at the beginning of a player's turn, the balls "on" are all remaining red balls. The player must therefore attempt to first hit and pot one or more red balls. For every red ball potted, the player will receive 1 point. When a red has been potted, it will stay off the table and the player can continue the break. If no red has been potted or a foul has been made, the other player will come into play.

In case one or more red balls have been potted, the player can continue the break. This time one of the six colours (yellow, green, brown, blue, pink and black) is the ball "on". Only one of these can be the ball "on" and the rules of the game state that a player must nominate the desired colour to the referee, although it is usually clear which ball the striker is playing and it is not necessary to nominate.

When the nominated colour is potted, the player will be awarded the correct number of points (yellow, 2; green, 3; brown, 4; blue, 5; pink, 6; black, 7). The colour is then taken out of the pocket by the referee and placed on its original spot. If that spot is covered by another ball, the ball is placed on the highest available spot. If there is no available spot, it is placed as close to its own spot as possible in a direct line between that spot and the top cushion, without touching another ball. If there is no room this side of the spot, it will be placed as close to the spot as possible in a straight line towards the bottom cushion, without touching another ball.

Because only one of the colours is the ball "on", it is a foul to first hit multiple colours at the same time, or pot more than one colour (unless a free ball has been awarded, see below).

After the nominated colour is potted, the red balls are "on" again.

If a player fails to pot a ball "on", it being a red or nominated colour, the other player will come into play and the balls "on" are always the reds, as long as there are still reds on the table.

The alternation between red balls and colours ends when all reds have been potted and a colour is potted after the last red, or a failed attempt to do so is made. All six colours have then to be potted in ascending order of their points value (yellow, green, brown, blue, pink, black). Each becomes the ball "on" in that order. During this phase, when potted, the colours stay down and are not replaced on the table, unless a foul is made when potting the colour, in which case the colour is respotted.

When the colours have been potted, the frame is over and the player who has scored most points has won it (but see below for end-of-frame scenarios).

Fouls

A foul is a shot or action by the striker which is against the rules of the game.

When a foul is made during a shot, the player's turn is ended and he will receive no points for the foul shot. The other player will receive penalty points.

Common fouls are:

• failing to hit any other ball with the cue ball
• first hitting a ball "not-on" with the cue ball
• potting a ball "not-on"
• potting the white (in-off)
• hitting a ball other than the white with the cue
• making a ball land off the table
• touching the cue ball with anything other than the tip of the cue (except while positioning the cue ball "in-hand"; while "in-hand" the cue ball may be touched by anything except the tip of the cue)
• playing a "push shot" - a shot where the cue ball is in simultaneous contact with the cue tip and another ball (except when playing the cue ball away from a "touching ball"; for this purpose a "touching ball" may refer to any ball, "on" or not.)
• playing a "jump shot" - a shot where the cue ball leaves the bed of the table and jumps over a ball before first hitting another ball
• playing a shot with both feet off the ground.

It is sometimes erroneously believed that if two balls are potted in one shot it is a foul. However, when the reds are "on", multiple reds can be potted and this is not a foul: the player scores 1 point per red.

Should a cue ball be touched with the tip while "in-hand", i.e. when breaking-off or playing from the "D" after being potted, a foul is not committed as long as the referee is satisfied that the player was only positioning the ball, and not playing, or preparing to play, a shot.

When a foul is made, the non-fouling player will receive penalty points equal to the value of the ball "on", or the value of any of the "foul" balls, or 4 points, whichever is highest. When multiple fouls are made in one shot, only the most highly valued foul is counted. Penalty points are therefore at least 4 points and at most 7.

Not hitting the ball "on" first is the most common foul. A player can make life difficult for his opponent by making sure he cannot hit a ball "on" directly. This is most commonly called "snookering" one's opponent or alternatively "laying a snooker" or putting the other player "in a snooker".

Because players receive points for fouls by their opponents, snookering one's opponent a number of times in a row is a possible way of winning a frame when potting all the balls on the table would be insufficient to ensure a win.

If a player commits a foul, and the opponent considers that the position left is unattractive, he may request that the offender play again from the resulting position.

Free ball

Free ball situation

A free ball is a player-nominated substitute for the ball on when the player is snookered by a foul. This is because the snooker in this case is produced by a foul and thus not considered legitimate. As such the player is allowed to pick any ball as a free ball, which is then effectively treated as the ball on, thereby voiding the illegitimate snooker. Once the free ball shot is taken legally, the game continues normally (although, if the offending player was asked to play the shot again, then the free ball is void, having to resolve the self-inflicted snooker).

For example, as illustrated in the provided picture, if the ball on is the final red, but is snookered by the black due to a foul, the player will be able to name the blue as the free ball. He could then pot the blue as if it were a red for one point. The blue will then be respotted, a nominated colour ball will be on, and normal play will resume.

Note that, as a natural corollary of the rules, the free ball is always a colour ball. If the ball on is a red, then by definition it cannot be snookered via another red, as it merely provides an alternative clean shot with another ball on. If the ball on is a red, and is snookered by a colour after a foul, then logically the red is either the final one or all reds are snookered by a colour ball, meaning the free ball has to be a colour. If the ball on is a colour ball that is snookered by a red, a previous red must have been successfully potted; the snooker therefore must be self-inflicted and cannot have occurred as the result of a foul. If the ball on is a colour that is snookered by another colour after a foul, all reds must have been already potted; thus the free ball still has to be a colour ball.

Interesting situations could occur if somehow both the free ball and the real ball on are potted. If a colour was the ball on (all reds were potted), and both the free ball and the actual ball on are potted, only the ball on is scored. The free ball is respotted while the actual ball on will stay off the table. This is the only time when attempting to pot a colour that two balls can be potted without a foul occurring, because technically speaking both of the potted balls are on.

If the ball on is red and both the free ball and a real red are potted, then each ball potted is scored as a red for a total of two points. The colour free ball is then respotted and the red remains off the table. By the same logic, it is allowed to cannon a free ball onto a real red to pot the latter (a plant). Going back to the picture above, the player could nominate the black as the free ball, and proceed to plant the real red using the black free ball; if the player somehow potted them both, two points would be awarded and the black would be respotted.

Not potting the free ball incurs no penalty, so the striker may play a snooker using the free ball, gratis. However, if said snooker is achieved by having the free ball obstructing the ball on, then the strike is a foul and a penalty of the value of the ball on is awarded to the opponent. The reason is that the free ball was to be treated as the ball on, and one cannot snooker a ball on by another ball on (following the same logic that a red cannot snooker another red when red is on). The only exception to this is when there are only two balls remaining on the table, namely pink and black. If the opposition somehow fouled trying to pot pink, and illegitimately snookered the striker with the black, then it is fair for the striker to snooker the opposition "back" with the free black ball.

A free ball scenario does not occur when the ball gets stuck at the edge of a pocket jaw (commonly referred to as "angled') in such a manner that the player is unable to hit any ball on. This is because according to the official snooker rules a ball is snookered only if its way is obstructed by balls not on. In this scenario, after a foul, the player may choose to either take the shot from the current position or ask the offender to play again, as per the usual rules on fouls.

Foul and a Miss

A foul and a miss will be called if a player does not hit the ball "on" first (foul) and is deemed by the referee to have not made the best possible attempt (miss). In this case, the opponent has the option to request that all balls on the table to be returned to their position before the foul, and require the fouling player to take the shot again.

The rule was introduced to prevent players from playing professional fouls (i.e., deliberately fouling so as to leave the balls in a safe position, reducing the risk of giving a frame-winning chance to the opponent). Multiple misses often occur because players attempt to hit a shot very softly or thinly in situations where a fuller contact might leave their opponent an easy potting chance. This can lead to an apparently easy escape being attempted several times, as players feel that it is better to concede many points but leave a safe position, than concede none and leave a frame-winning chance.

Note that "best attempt" here has a couple of elements. Firstly, the shot selection must be the easiest to be achieved, so deliberately taking a difficult shot to foul tactically will be still liable to be called a miss. Secondly, sufficient strength must be put into the shot such that the cue ball can even reach the ball "on" (it's possible for the referee not to call a miss if a striker would or did overshoot, but undershooting always results in a miss). Finally, the striker must try to hit the ball "on" as best as he can, getting the cue ball as near to the target as possible. All three of these elements must be present for a striker to be considered to have made a "best attempt", and not just the third element.

There are three situations where a miss will not be called even if the striker failed to do a "best attempt":

1)If either of the players is in need of penalty points to win the frame, or if either players would be in need of further penalty points to win the frame after the current penalty is applied, then a miss will never be called. This is to prevent the score difference from increasing indefinitely due to misses in worst-case scenarios.

2)If the points on the table are equal to the score difference, either before or after the penalty is applied, then a miss may not be called, should the referee believe that the foul was not on purpose. This can prevent the score difference from decreasing too much, at the discretion of the referee.

3)If it is physically impossible to play a legal shot, then it must be assumed that the striker is trying their best already, though the striker must still put sufficient strength in the stroke such that the cue ball would reach its target were it not due to the obstruction. This can happen if the cue ball was completely snookered - since jump shots are fouls in the first place, there is no other way this scenario could end.

A special case occurs after a striker fouls and misses in a non-snookered scenario -- that is, when he fails to hit a ball "on" when there is a clear path to the ball or part of the ball. Should the opposition choose to have the offender play from the position prior to the missing stroke under this situation, then a further failure to provide a best attempt will be called foul and a miss regardless of score difference. A warning is issued, and a third failure will forfeit the frame to the opposition.

The end of a frame

A frame normally ends in one of three ways:

• A concession, when one player gives up due to being too far behind to have a realistic chance of winning the frame. Concession before the snookers-required stage may be interpreted as ungentlemanly conduct and result in a penalty of a second frame being applied.
• The final black is potted legally (including after a respot), and this does not leave the score tied.
• When the black is the only object ball remaining, and the striker leads by more than seven points, the striker may claim the win, but may also elect to proceed with potting the black, for example to complete a high-scoring break.

There are three less common ways to end a frame:

• A foul on the black, when the black is the only ball left. It is sometimes wrongly assumed that play continues after a foul on the black if there are fewer than seven points between the scores. This is not the case: the player who is in the lead following the assessment of a penalty after a foul when only the black remains is the winner.
• Failure to hit a ball "on" three times in a row, if the player has a clear sight of the ball. The referee will warn a player after a second such miss that a third miss will mean that the opponent will be awarded the frame. This rule does not apply if the player is snookered. As missing due to avoiding a direct shot on a ball is usually a tactical, rather than skill-related, outcome, this rule is rarely invoked, as a player will simply hit the ball directly on the third shot.
• If the referee deems a player is taking too long to take the shot, the player may be warned. If the player continues to hesitate, the frame may be awarded to the other player at the discretion of the referee. In practice, a delay of over two minutes can result in such a forfeiture.

If the score is tied after the final black is potted, the black is "respotted" and the cue ball put "in hand". The referee will then toss a coin, with the player winning the toss choosing who will take first strike at the black. Play then continues normally until the black is potted or another frame-ending situation occurs.

Maximum break

Main article: Maximum break

The highest break that can be made under normal circumstances is 147. To achieve that, the player must pot all 15 reds, with the black after every red, followed by potting the six remaining colours. This "maximum break" of 147 rarely occurs in match play. The fastest maximum break in a tournament was achieved during the World Championships on April 21, 1997, by Ronnie O'Sullivan against Mick Price in 5 minutes and 20 seconds.

If an opponent fouls before any balls are potted, and leaves the player a free ball, the player can then nominate a colour and play it as a red ball. Then, black can be nominated as the next colour. This means it is actually possible to score the value of 16 reds and blacks (16 * 8), plus the values of all the colours (27), which equals 155 points scored. Under tournament condition, Jamie Burnett achieved 148 points.

The highest possible score, as distinct from the highest possible break, is unlimited and depends on the value of points scored from the opponent's foul shots when added to the player's own scored points (which may not require the highest break). However, the highest possible score from a single visit clearance is 162 (foul on the black, followed by a free ball treated as a red, as above).