The standard professional game is 501. Each player starts on 501, throws three darts per visit, and subtracts what those darts score from the running total. The first to reduce the score to exactly zero wins the leg — but the dart that takes the score out must land in a double, either one of the twenty double beds around the outer rim or the 50 inner bullseye, which counts as double 25. Reaching zero any other way, dropping below zero, or leaving exactly one is a bust: the visit is void and the score reverts to what it was before the throw.
The board itself supplies all the complexity the sport needs. Twenty wedges radiate from the bull, numbered in a deliberately hostile order so that the biggest scores sit beside the smallest. A dart in the thin outer ring doubles the wedge's value; a dart in the thin inner ring trebles it. The treble 20 pays 60, so three darts can produce a maximum of 180, and the whole professional game is built on how reliably a player can find that bed and then convert what is left into a double.
Scoring at a glance
Core rules
The board and its numbering
A tournament board is a bristle board 451 millimetres in diameter with a scoring area of 340 millimetres, divided into twenty wedges by thin metal or blade wire. The sequence running clockwise from the top is 20, 1, 18, 4, 13, 6, 10, 15, 2, 17, 3, 19, 7, 16, 8, 11, 14, 9, 12, 5. The arrangement is deliberately punitive: every high number is flanked by two of the lowest, so 20 sits between 5 and 1, and 19 between 3 and 7. The narrow outer ring doubles a segment, the narrow inner ring trebles it, the 25 ring scores 25 and the inner bull scores 50.
The oche and the throw
Players throw from behind a raised marker called the oche, set 2.37 metres (7 ft 9.25 in) from the face of the board, measured horizontally, with the centre of the bullseye 1.73 metres above the floor. A player may lean over the oche but must not step on or beyond it. Each visit consists of three darts thrown one at a time, and darts may be thrown as quickly or as slowly as the player likes within the tournament's pace-of-play rules. The player who is not throwing stands behind the thrower and must remain still.
Scoring a visit
The referee or the electronic system totals the three darts and subtracts them from the player's remaining score. Only darts that stay in the board count, so a dart that bounces out of the wire or falls from the board scores nothing and may not be re-thrown. The score is called aloud, and the player is expected to leave the darts in the board until it has been called and displayed. A player may stop after one or two darts if the score is already checked out, which is how nine-dart legs and short checkouts are completed.
Finishing on a double
The leg ends only when a player reduces their score to exactly zero with a dart in a double bed or the inner bull. From 40 the natural route is a single dart at double 20; from 32, double 16; from 170, the maximum, treble 20, treble 20 and bull. Because the finish must be exact, the two darts before it matter almost as much: engineering a preferred double from an awkward number is a distinct skill known as the setup dart, and checkout percentage is tracked as closely as scoring average.
Busting
A visit is busted if a dart reduces the score below zero, leaves exactly one — since one cannot be finished on a double — or brings the score to zero without landing in a double. When a bust occurs the rest of the visit is forfeited and the score returns to what it was at the start of that throw, so nothing is lost but the turn. This makes the arithmetic of leaves crucial: a player on 50 who hits a single 20 is left on 30, but one who hits a treble 20 has busted.
The bull-up and the throw
Because the player who throws first in a leg needs only their own darts to win it, the throw is a tangible advantage, and legs alternate strictly. The right to start a match is decided by a bull-up, or diddle for middle: each player throws one dart at the bullseye and whoever lands closest throws first. In sets play the throw also alternates from set to set. Winning a leg against the throw is called a break, and matches are commonly described in terms of holds and breaks in the same way as tennis.
Legs, sets and match formats
Most professional matches are played over legs — best of eleven, first to six, and so on. The World Championship and a handful of other events use sets, each set being the first to three legs, with the final played as first to seven sets. Some majors add their own twists: the World Grand Prix requires a double to start the leg as well as to finish it, and the Grand Slam of Darts opens with round-robin groups. Formats also govern whether a deciding leg is played with the throw or after a fresh bull-up.
Equipment rules
A dart may weigh no more than 50 grams and measure no more than 300 millimetres overall, though almost all professionals use barrels between 20 and 26 grams. A dart has four parts — point, barrel, stem and flight — and players change stems and flights constantly to alter how the dart sits in the air. Steel-tip darts are used on bristle boards in the professional game; soft-tip darts with plastic points are used on electronic boards that score automatically, the dominant format across Japan, South Korea and much of the United States.
Fouls & penalties
Bust and the invalid finish
Going below zero, leaving a score of one, or hitting zero with anything other than a double all void the visit. The score reverts to the figure at the start of the throw and the opponent takes their turn. There is no additional penalty, but a bust in a tight leg is usually decisive because it hands over a full three darts. Busting on the first dart of a visit forfeits the other two, so players on awkward leaves often aim deliberately low.
Foot faults
Stepping on or over the oche invalidates the throw. A referee will normally warn a player first, but darts thrown after a warning can be ruled no score. The rule is enforced more loosely at grassroots level than on television, where a raised oche makes encroachment obvious. Players are permitted to lean well over the line, and several of the sport's most distinctive stances involve extreme forward lean with the rear foot anchored behind it.
Darts thrown out of turn or after the call
A dart thrown when it is not the player's turn does not score and cannot be replaced. Once the referee has called the score, the visit is closed. Players are also required to leave their darts in the board until the score is called, and removing them early can forfeit the right to challenge a miscall. Scoring disputes are settled by the referee, whose ruling on what is in the board is final.
Bounce-outs and fall-outs
A dart that rebounds from the wire, from another dart, or from the board surface scores nothing and may not be thrown again. The same applies to a dart that sticks briefly and drops before the score is called. Modern blade-wire boards, which replaced the older round wire, have made bounce-outs far rarer, but they still occur and they still consume one of the three darts — which is why a bounce-out on a checkout attempt is one of the sport's crueller moments.
Distraction and unsporting conduct
The non-throwing player must stand behind the thrower and avoid movement, noise or gestures that could distract them. Deliberate coughing, celebrating during an opponent's throw, or crowding the oche can draw a warning, a formal caution and ultimately disqualification. Tournament rules also cover deliberate slow play, refusal to continue and abuse of officials. Disciplinary panels at the PDC and WDF have issued fines and suspensions for on-stage confrontations and for conduct away from the board.
Doping, alcohol and the playing area
Professional darts is subject to anti-doping testing, and beta blockers — which suppress the tremor that ruins a throw — are specifically prohibited. Alcohol has been banned in the playing area since the late 1980s, when the sport's collapse in television coverage was blamed partly on the sight of players drinking on stage. Players may take water or soft drinks to the oche, and tournaments enforce timed walk-ons, dress codes and a ban on smoking anywhere in the arena.
Match format
A professional match is a race, not a clock. In leg formats the first player to reach the required number of legs wins, with legs alternating throw, so a best-of-eleven is decided by whoever gets to six first and usually turns on a single break. The World Championship instead uses sets: three legs win a set, and the final is the first to seven sets, meaning a champion may need to win more than sixty legs in an evening. Longer formats reward endurance and punish the player whose average slides in the fourth hour.
Individual events layer their own rules on top. The World Grand Prix uses double-in as well as double-out, which turns the opening of every leg into a nerve test and produces averages far below any other major. The Grand Slam of Darts begins with round-robin groups. The UK Open uses an open draw redrawn round by round, so a Tour Card holder can be pulled out against a qualifier from a pub team. Premier League Darts runs as a weekly league phase with nightly knockouts, and the World Cup of Darts is contested by two-player national teams across singles and doubles.
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