Explainer · evergreen
Why does darts start at 501? The odd number that makes the finish
In one line: The double-out rule, what an odd start number does to the maths, and why 501 became the standard rather than a round 500.
Every other sport counts up. Darts counts down from a deliberately awkward number, and the awkwardness is the point. The short version: 501 is odd, the finish must be a double, and those two facts together turn the last three darts of a leg into the most tense sequence in the sport.
The double-out rule comes first
Before asking why 501, understand what a leg requires: the score must reach exactly zero, and the finishing dart must land in a double — the thin outer ring, or the inner bullseye, which counts as a double. Bust the score below zero or finish on a single and the score reverts to what it was before the turn. The rule is what makes darts finishing a distinct skill from darts scoring: hitting 180s is power arithmetic; finishing 121 (T20, T11, bull) is a different craft. The mechanics and history are set out on Wikipedia's darts entry.
What the odd number does
Start at 500 and a player could, in theory, chase the same target all the way down: three treble 20s per visit, always the same bed. Start at an odd number and that becomes impossible — every treble is worth an even 60, so an odd remainder guarantees a switch of target somewhere in the finish. The odd start forces variety, and variety is where legs are won and lost. It is the same design instinct behind requiring a double to finish: both rules exist to make the endgame a test rather than a formality.
Why 501 became the standard
Honest answer: convention, crystallised by tournament history. Shorter starts — 301, and even 101 in some formats — survive as variants, and some games add a double-in requirement, but 501 emerged as the professional standard because it balances leg length against television: long enough that comebacks are possible, short enough that a best-of-legs match keeps changing hands. The perfect leg it produced — nine darts from 501 to zero, achieved a handful of times on television — became the sport's holy grail, tracked on Wikipedia's nine-dart finish entry. That nine-dart chase only exists because of the number: 501 divides perfectly into three maximum visits plus a checkout.
What a beginner should take from it
The count-down is not trivia; it is strategy. Good players spend most of a visit scoring, then spend the last visit setting up a finish — leaving a score they can close with doubles they actually hit, most famously 40 (double 20) or 32 (double 16), because missing leaves a single below and another dart in hand. Watch a professional's third visit and you are watching someone doing this arithmetic at speed. It is the same genre of question as the scoring quirks in other sports — see how golf scoring works for another system built on odd conventions that turned out to work.
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