Swimming (World Aquatics) — Official Rules

Swimming is an individual and relay racing sport governed worldwide by World Aquatics (formerly FINA). Competitions are contested over fixed distances in one of four recognised strokes - Freestyle, Backstroke, Breaststroke and Butterfly - plus Individual Medley (all four strokes by one swimmer) and Medley/Freestyle Relays (four swimmers per team). There is no clock-limited match, no periods and no scoring of points during the swim; the swimmer who covers the announced distance legally in the shortest time wins. Recognised individual distances range from 50 m to 1500 m in a 50 m (long course) or 25 m (short course) pool.

Placing is determined solely by elapsed time: the swimmer or relay team recording the shortest legal time over the distance finishes first. When Automatic Officiating Equipment is used, the recorded times determine the winner, all placings and the time for each lane, and take precedence over the timekeepers' decisions (SW 11.1). In the event of equal times, all swimmers who record the same time to 1/100 of a second are given the same placing - a tie (SW 11.2). A disqualified swimmer is recorded as disqualified with no time or place (SW 11.4).

A swimming meet is conducted by a team of officials (SW 2): the Referee has full control and authority over all officials, decides all questions whose settlement is not otherwise covered, and disqualifies swimmers for violations; the Starter controls the swimmers from the moment the Referee hands them over until the race begins; Inspectors of Turns (one per lane at each end) check turns and finishes and the relay take-over; Judges of Stroke check stroke legality; Timekeepers and the Chief Timekeeper record manual times; the Control-Room Supervisor oversees the automatic timing and reviews the relay-exchange print-outs. Officials make their decisions autonomously and independently of one another (SW 2.13).

A competition pool is 50.000 m (long course) or 25.000 m (short course) long; when touch panels are fitted the pool must be longer so that the distance between panels is exactly the nominal length (FR 2.1). Each lane is at least 2.5 m wide, with two spaces of at least 0.2 m of water outside the first and last lanes (FR 2.5). Olympic-standard pools provide 10 lanes (lanes 0-9), of which the eight centre lanes are normally used for racing. End walls are vertical and parallel and form right angles with the surface and lane lines (FR 2.4).

Minimum water depth is 1.35 m from 1.0 m to at least 6.0 m from the end wall where starting platforms are used (FR 2.3); a depth of 2.0 m or more is recommended for high-level facilities. The water must be kept at a constant level with no appreciable current or turbulence, allowing inflow/outflow only as required by health regulations. The water temperature must be maintained between 25 C and 28 C for swimming competition.

Lane ropes extend the full length of the pool, each made of floats joined so as to mark the lanes and damp turbulence. The floats must be a distinct colour for the 5.0 m nearest each end wall and, critically, at the 15-metre mark from each end wall the floats shall be a distinct colour (FR 2.6) - this marks the limit of the permitted underwater phase. In 50 m pools the floats also mark the 25 m midpoint. Lane lines on the pool floor end 2.0 m from each end wall with a distinctive cross (FR 2.14).

The starting platform stands 0.5 m to 0.75 m above the water surface with a top surface of at least 0.5 m x 0.5 m covered in non-slip material, and a slope of not more than 10 degrees (FR 2.7). Backstroke start grips are fitted 0.3 m to 0.6 m above the water surface. Loudspeakers for the start are mounted at each platform; the start signal and the command "take your marks" are given in English at World Aquatics events (SW 4.3).

An optional backstroke ledge may be installed for backstroke and medley-relay backstroke starts. Under the current regulations the ledge must be a minimum of 60 cm in length (reduced from 65 cm in the 2025 update), 8 cm in height and 2 cm in width with a 10-degree slope, and adjustable up to 4 cm above or 4 cm below the water surface (FR 2.10). When a ledge is used the toes of both feet must be in contact with the end wall or the face of the touch panel; bending the toes over the top of the touch panel is prohibited (SW 6.1). An inspector installs and removes the ledge after the start (SW 6.2).

A false start rope may be suspended across the pool not less than 1.2 m above the water, 15.0 m in front of the starting end, to be dropped to recall a faulty start (FR 2.11). Backstroke turn-indicator flags are hung across each end 5.0 m from the wall to help backstrokers locate the wall. No swimmer may use or wear any device or swimsuit that aids speed, buoyancy or endurance - webbed gloves, flippers, fins, power bands and adhesive substances are forbidden; goggles may be worn (SW 10.8). The 2025 update also permits specially designed period-friendly swimwear for women, subject to the equipment rules.

Swimmers are seeded into heats by their best competitive (entry) times for the event (SW 3). If there is one heat it is seeded as a final and swum only in the finals session. With two or more heats, the fastest swimmers are spread across the last heats. Within each heat lanes are assigned in descending order of submitted time, fastest in the centre lane then alternating outward - so the seeded order in an 8-lane pool is centre lanes (4, 5), then (3, 6), (2, 7), (1, 8). This spearhead pattern places the strongest swimmers in the middle.

After preliminary heats the fastest swimmers advance: for events with semifinals the top 16 qualify to two semifinals, and the top 8 then advance to the final (SW 3.2). Distance events (e.g. 800 m and 1500 m) are normally timed finals swum directly from heats with no semifinals. Swimmers tying for the last qualifying place swim off to decide who advances (SW 3.3). The final lanes are then re-seeded by semifinal/heat time using the same centre-first pattern.

Freestyle, Breaststroke, Butterfly and Individual Medley start with a dive. On the Referee's long whistle the swimmers step onto the starting platform and stay there. On the Starter's command "take your marks" they immediately take a starting position with at least one foot at the front of the platform (the position of the hands is not relevant). When all swimmers are stationary, the Starter gives the starting signal (SW 4.1).

Backstroke and Medley-Relay backstroke legs start from the water. On the Referee's first long whistle the swimmers enter the water; on the second long whistle they return without undue delay to the starting position - lined up in the water facing the wall, both hands holding the start grips (SW 6.1). Standing in or on the gutter, or bending the toes over the lip of the gutter, is prohibited. After "take your marks" and when all are stationary, the Starter gives the signal (SW 4.2).

Any swimmer starting before the starting signal shall be disqualified (SW 4.4). World Aquatics uses a strict one false start = disqualification rule: there is no warning. If the start signal has already sounded, the race continues and the offender is disqualified on completion; if the false start is detected before the signal, the signal is withheld, the remaining swimmers are recalled, and the Referee repeats the start (beginning at the second long whistle for backstroke). The disqualification for starting before the signal must be observed and confirmed by both the Starter and the Referee (SW 2.1.6).

In a Freestyle event the swimmer may swim any style (in Individual Medley/Medley Relay, freestyle means any style other than backstroke, breaststroke or butterfly). Some part of the swimmer must touch the wall on completing each length and at the finish (SW 5.2). Some part of the swimmer must break the surface throughout the race, except that the swimmer may be fully submerged during the turn and for not more than 15 m after the start and each turn - by the 15 m mark the head must have broken the surface (SW 5.3). Standing on the bottom is allowed but walking is not (SW 10.5).

After the signal and after each turn the swimmer must push off and swim on the back throughout the race; the body may roll up to, but not including, 90 degrees from horizontal, and the head position is not relevant (SW 6.3). The swimmer must break the surface except for not more than 15 m after the start and each turn (SW 6.4). At a turn the swimmer must touch the wall; the shoulders may turn past vertical to the breast for one continuous single or simultaneous double-arm pull to start the turn, but the swimmer must be back on the back when leaving the wall (SW 6.5). At the finish the swimmer must touch the wall while on the back (SW 6.6).

The stroke cycle is one arm stroke then one leg kick, in that order, with all arm and all leg movements simultaneous and on the same horizontal plane (SW 7.2). After the start and each turn one full arm pull back to the legs is allowed while submerged, and a single butterfly (dolphin) kick is permitted before the first breaststroke kick (SW 7.1). The feet must turn outwards during the propulsive kick; alternating or downward dolphin kicks are otherwise forbidden (SW 7.5). During each cycle some part of the head must break the surface before the hands turn inward at the widest part of the stroke (SW 7.4). At each turn and the finish the touch must be made with both hands separated and simultaneously (SW 7.6).

From the first arm stroke after the start and each turn the body is kept on the breast (rolling onto the back is not allowed except during the turn). Both arms must be brought forward together over the water and back together under the water throughout the race (SW 8.2). All up-and-down leg movements must be simultaneous (a dolphin kick); a breaststroke kick is not permitted (SW 8.3). At the start and each turn one or more leg kicks and one arm pull underwater are allowed to surface, and the swimmer may be fully submerged for not more than 15 m after the start and each turn before the head must break the surface (SW 8.5). At each turn and the finish the touch must be made with both hands separated and simultaneously (SW 8.4).

In Individual Medley events the swimmer covers the four strokes in the order Butterfly, Backstroke, Breaststroke, Freestyle, each over one quarter (1/4) of the distance (SW 9.1). Each section must be finished according to the rule of the stroke concerned (SW 9.3). Because backstroke is defined only as being on the back, leaving the wall on the back into the freestyle leg covers more than a quarter as backstroke and is a disqualification. (In Medley Relays the order is different: Backstroke, Breaststroke, Butterfly, Freestyle - SW 9.2.)

Each individual race is a separate gender event (SW 10.1). A swimmer must remain and finish in the same lane in which they started (SW 10.3). At every turn the swimmer must make physical contact with the end wall; the turn must be made from the wall and it is not permitted to take a step from the bottom (SW 10.4). Pulling on the lane rope is not allowed (SW 10.6). Obstructing another swimmer by crossing into another lane or otherwise interfering disqualifies the offender, and an intentional foul is reported to the Member (SW 10.7). After finishing, a swimmer must leave the pool promptly without obstructing others still racing (SW 10.14).

A relay team has four swimmers (SW 10.10); Mixed Relays must be two men and two women (split times from mixed relays cannot be used for records or entries). The decisive rule is the take-over (exchange): a relay team is disqualified if a swimmer's feet lose contact with the starting platform before the preceding team-mate touches the wall (SW 10.11). The tolerance is zero - automatic equipment measures the exchange and any negative differential (leaving early) is a disqualification. The nominated order of competing must be followed; failure to swim in the listed order is a disqualification (SW 10.13).

A relay team is disqualified if a swimmer other than the one designated for that length enters the water before all teams have finished (SW 10.12). Each relay member may compete only once per relay; substitutions are allowed only for a documented medical emergency, and the team composition may otherwise be changed between heats and final only from the properly entered list (SW 10.13). In a relay disqualification, legal splits up to the moment of the violation are still recorded in the official results (SW 11.5). 50 m and 100 m splits of the lead-off swimmer are recorded and published (SW 11.6).

Times recorded by Automatic Officiating Equipment determine the winner, all placings and each lane's time, and take precedence over the timekeepers (SW 11.1). The equipment is activated by the Starter and records elapsed time and the relay take-over (FR 4). Touch panels measure at least 2.4 m wide and 0.9 m high (0.3 m above and 0.6 m below the surface), are sensitive on the front face and top edge, and must not be activated by water turbulence (FR 4.4). If the equipment breaks down or a swimmer fails to activate it, the timekeepers' (backup) times become official (SW 13.3).

Automatic times are recorded only to 1/100 of a second; if timing to 1/1000 is available the third digit is neither recorded nor used to decide time or placing, so swimmers level to 1/100 share the placing (SW 11.2). Where there is no automatic equipment, official manual times use three timekeepers per lane: if two of three agree, that is the time; if all three differ, the middle (median) time is official; with only two watches working, their average is official (SW 11.3). Manual times are also registered to 1/100 of a second.

World Records and World Junior Records are recognised in both 50 m and 25 m courses for the standard distances - Freestyle 50/100/200/400/800/1500 m, Backstroke/Breaststroke/Butterfly 50/100/200 m, Individual Medley 200/400 m (and 100 m short course), and relays (SW 12.1-12.2). Records must be set in scratch competition or a sanctioned individual race against time, with the lane length certified by a surveyor (SW 12.6), and are accepted only when timed by Automatic Officiating Equipment (semi-automatic only on malfunction) (SW 12.8). Relay record holders must be of the same nationality (SW 12.4).

The Referee disqualifies a swimmer for any violation of the rules personally observed or reported by an Inspector of Turns or Judge of Stroke on a signed card (SW 2.1.7, SW 2.6.6, SW 2.7.3). Common disqualifications use World Aquatics rule codes: SW 4.4 false start, SW 5.3 / 6.4 / 8.5 breaking the 15 m underwater limit, SW 6.x not on the back / illegal backstroke turn, SW 7.x non-simultaneous breaststroke or one-hand touch, SW 8.x illegal butterfly or one-hand touch, SW 9.1 medley order, and SW 10.11 early relay exchange. A disqualified swimmer is recorded with no time or place (SW 11.4).

A protest may be lodged with the Referee if the rules and conditions of the competition are not observed, if conditions endanger swimmers, or against the Referee's own decision - generally within 30 minutes of the result being announced, accompanied by the prescribed deposit (refunded if upheld). The Control-Room Supervisor may review the relay-exchange print-outs and any video backup before confirming a take-over disqualification (SW 2.2.3-2.2.4). Photo-finish and timing prints are used to resolve close finishes and ties. The Referee's ruling on a point of fact is final, while points of rule interpretation may go to a Jury of Appeal.

Following its rebranding from FINA, World Aquatics has consolidated the previously separate Swimming, Facilities and General rules into one Competition Regulations document, the current version dated February 2026 (in force from 18 February 2026). The substantive swimming, pool and timing rules above are carried forward unchanged in numbering convention (SW / FR codes remain the working references for officials), with periodic updates approved by the World Aquatics Bureau.

The 2025 update introduced several headline changes carried into 2026: the backstroke ledge minimum length was reduced from 65 cm to 60 cm (FR 2.10); the swimwear/equipment rules now permit specially designed period-friendly swimwear for women during menstruation; ISO-approved goggles follow a simplified accessory-approval path; open-water wetsuit design rules were given more flexibility; and the three fixed annual deadlines for equipment-approval applications were removed in favour of a rolling process.