Duckworth-Lewis-Stern: The Rain Rule Nobody Understands (Explained)

The Duckworth-Lewis-Stern (DLS) method is the mathematical formula used to set revised targets in limited-overs cricket when rain interrupts play. Introduced in 1997 (as Duckworth-Lewis) and updated by Steven Stern in 2014, it is fairer than the old methods — but widely misunderstood.

Why DLS was needed

Before DLS, rain rules used methods like 'most productive overs' — which were unfair. Most infamously, in the 1992 World Cup semi-final, South Africa needed 22 runs off 13 balls when rain reduced them to needing 22 runs off 1 ball. This absurdity led to a search for a fairer mathematical system.

The core concept: resources

DLS treats a cricket innings as two resources: overs remaining and wickets in hand. At the start of an innings, a team has 100% of resources. As overs are bowled and wickets fall, resources decrease. Rain takes away overs — and therefore resources. DLS adjusts the target based on the proportion of resources each team had available.

Team A bats 50 overs and scores 280.
Rain reduces Team B's innings to 30 overs.
Team B has approximately 75.1% of the resources Team A had.

DLS target for Team B = 280 × (75.1/100) = 210 + 1 (rounded) = 211 to win.

If Team B scores 210, the match is a tie. 211+ wins.

When it applies

DLS applies when: (a) the first innings is completed normally but the second innings is interrupted or reduced, OR (b) the first innings is also affected. If the first innings is shortened, DLS uses the par score concept — what a team would typically score with the available resources. If Team A bats 30 overs instead of 50, their 'par score' concept adjusts Team B's target accordingly.

Why DLS is complex

The resource table used by DLS is not publicly disclosed in full — it is based on statistical modelling of thousands of cricket innings. The table recognises that the value of wickets varies: losing wickets early in 50 overs is more damaging than losing them in the 40th over. DLS accounts for this non-linearity, which no simple formula can capture.