501 darts rules: how the classic works

The odd number stops a leg being played out purely on doubles — at least one odd number has to be hit. Historically the value comes from English pubs, and it has stuck as a good balance between tension and playing time.

Nine. A nine-darter is the mathematical minimum — for example 180, 180, then 141 finished via treble 20, treble 15 and double 18. In practice a casual player needs 25 to 40 darts per leg — which matches an average between 40 and 60.

The average points scored per turn, meaning per three darts. Casual players often sit between 40 and 60, a strong club player between 60 and 80, professionals above 95. It is the standard number for comparing playing strength.