The object is to hit the ball onto the front wall, above the tin and below the out line, so that the opponent cannot return it before it bounces twice on the floor. Both players occupy the same court and hit alternately, and the ball may touch any combination of side and back walls on the way to the front wall or on the way back. A rally ends when a player fails to make a good return, hits the ball down into the tin, hits it out, or lets it bounce twice.
Squash is governed by the World Squash Federation's Rules of Singles Squash, most recently overhauled in 2019, with the professional game refereed under PSA-specific conditions. Because two players share one enclosed space, the rules devote more attention to interference than to anything else: a whole vocabulary of lets, strokes and no-lets exists to decide who was entitled to the ball and who failed to get out of the way. Learning those three words is learning most of the sport's law.
Scoring at a glance
Core rules
The court and its lines
A singles court is 9.75 meters long and 6.4 meters wide. The front wall is playable from the top of the tin, 0.48 meters up, to the out line 4.57 meters above the floor; the back wall is playable to 2.13 meters, and the side walls slope between the two. The short line runs across the court 5.44 meters from the front wall, the half-court line splits the rear half, and two service boxes 1.6 meters square sit in the back quarters. Any ball touching an out line or the boundary above it is out.
The serve
The server must keep at least one foot entirely inside a service box, touching no line, and may serve from either box at the start of a game, alternating after each point won. The ball must strike the front wall between the service line, 1.78 meters up, and the out line, then rebound into the opposite back quarter unless the receiver volleys it. There is no second serve: a fault loses the rally outright. Serving is therefore a genuine tactical weapon, and the high lob serve that dies in the back corner is the most common opening in the professional game.
Making a good return
After the serve, the striker must hit the ball before it bounces twice and send it to the front wall above the tin and below the out line. The ball may hit any number of side or back walls first — the boast, the three-wall and the corner nick all exploit this — and may hit the walls after the front wall too. It may not hit the floor before reaching the front wall, nor touch the striker or their clothing. Volleying is legal at any time except on the serve return before the ball has reached the front wall.
Point-a-rally scoring
Games are played to 11 points under point-a-rally scoring, in which either player scores on any rally regardless of who served. At 10-10 a game continues until one player leads by two. Matches are best of five games. The men's professional tour adopted PAR to 11 in 2004 and the WSF extended it to all levels from the 2008-09 season, replacing the old English system in which only the server could score and games ran to nine. The change shortened matches, sharpened the value of the serve and pushed players toward attacking earlier.
The ball and the racket
Balls are hollow rubber, 39.5 to 40.5 millimeters in diameter and 23 to 25 grams, graded by colored dots: blue and red bounce most and suit beginners, single yellow is slow, and the double-yellow dot, standardized around 2000, is the extra-slow professional ball that must be warmed by rallying before it plays properly. Rackets may be no longer than 686 millimeters, no wider than 215 millimeters, no more than 500 square centimeters of strung area and no heavier than 255 grams. Protective eyewear is mandatory for juniors in most federations and for all doubles.
Clearing and the right to the ball
After playing a shot, a player must give the opponent unobstructed access to the ball, a fair swing and a direct path to hit it to any part of the front wall. This obligation to clear is the sport's central duty and the reason court position matters so much: a player who has left the ball loose must vacate the middle immediately. Failure to clear does not merely spoil a rally, it is penalized, and the severity of the penalty depends on how good the interfered player's shot would have been.
The knock-up and match conduct
Players share a five-minute knock-up before a match, changing sides after two and a half minutes, primarily to warm the ball into its playing range. Ninety seconds are allowed between games. A player who is injured by their own doing gets no recovery time; a self-inflicted bleeding injury allows a short period to stop the bleeding, while an injury caused by the opponent hands the injured player recovery time and, in some cases, the game. Referees may also stop play to change a broken ball or clear sweat from the floor.
Officiating and video review
Recreational squash is largely self-refereed, with players calling their own interference and agreeing lets. Professional events use a three-referee system: a central referee makes the call, and two side referees vote, with the majority deciding — a structure adopted to reduce the arbitrariness that plagued single-referee decisions. The PSA has also introduced video review, allowing a player to challenge a call a limited number of times per match, with replays checking the bounce, the tin and the out line rather than the subjective interference judgment itself.
Fouls & penalties
Let
A let is a replayed rally, awarded when interference occurred but the outcome was not clearly decided by it. The typical case: the striker was slowed by the opponent's position, the opponent made every effort to clear, and the striker would have made a good return but not a winning one. A let is also the normal ruling when a returning ball strikes the opponent on its way to the front wall, when a player is distracted, or when the ball breaks mid-rally. Lets score nothing and reset the point.
Stroke
A stroke awards the rally, and therefore the point, to the interfered player. It is given when the opponent failed to make every effort to clear, when the striker would have hit a winning return, when the striker's swing was blocked, or when the ball would have struck the opponent on a direct path to the front wall. The stroke is squash's great deterrent: without it, a player could simply stand on the ball's path. Learning to move off the T so as not to concede strokes is a basic professional skill.
No let
No let means the rally is lost by the player who asked for it. It is given when the striker could not have reached the ball in any case, when the interference was minimal and did not affect the outcome, when the player made no genuine effort to play the ball, or when the request is judged a fishing expedition for a cheap point. The 2019 rules explicitly discourage speculative appeals, and referees at professional level increasingly reward players who keep rallying rather than stopping.
Dangerous play and excessive swing
A player whose swing is excessive, or who plays a shot that endangers the opponent, may lose the stroke even if the opponent was standing close. Turning — following the ball around behind oneself before striking — is permitted, but if the striker turns and the ball would hit the opponent, the ruling is normally a let rather than a stroke, and a striker who hits the opponent after turning may lose the rally. The referee's overriding duty is safety, and dangerous play can be penalized regardless of who was technically obstructing.
Conduct penalties
Referees enforce a four-step ladder for misconduct: conduct warning, conduct stroke, conduct game and conduct match. Racket abuse, audible or visible dissent, deliberate delay, excessive appealing, foul language and physical intimidation all fall under it. Time-wasting is policed strictly, since the ball cools rapidly and a player can gain an advantage simply by slowing the game. The ladder is not strictly sequential — a serious first offence can go straight to a conduct game or match.
Down, out and not up
Three faults end rallies without any interference question. Down means the ball struck the tin or the floor before reaching the front wall. Out means it hit the out line or the wall above it, or left the court entirely. Not up means the ball bounced twice before it was struck, was carried or double-hit, or touched the striker or their clothing. In professional play, video review most often concerns exactly these three, since a ball skidding off the tin and a perfect nick can look identical at full speed.
Match format
A professional match is best of five games to 11 points, with 90 seconds between games and a five-minute knock-up beforehand. Elite matches typically run 45 to 70 minutes, though five-game contests regularly pass 90 minutes, and there is no clock, no substitution and no coaching during a game — a coach may speak only in the 90-second interval. Draws in world tour events are straight knockout, seeded from the PSA world rankings, which are calculated on a rolling basis across a defined number of the player's best results rather than a calendar-year points race.
Beyond singles, squash keeps several living variants. Squash doubles is played on a wider court, 7.6 by 13.7 meters, and remains popular in North America, where hardball doubles survives as a distinct code with its own championships. Team competition, from the biennial World Team Championships to national leagues and the American collegiate circuit, is contested as a series of individual matches, usually best of five or three ties, with the aggregate deciding the result. The Los Angeles 2028 Olympic programme will feature singles events for men and women.
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