The DLS Method Explained Without the Maths Degree

Nothing baffles new cricket fans like a rain delay ending with the words "revised target". The Duckworth-Lewis-Stern method, DLS for short, is the formula that produces those targets, and while the full mathematics is genuinely complex, the idea behind it is simple and fair.

The problem it solves

Limited-overs cricket promises each side one innings of equal length. Rain breaks that promise. If a chasing team loses 20 of its 50 overs, simply scaling the target down by overs, chase 60 percent of the runs in 60 percent of the overs, fails, because it ignores wickets. A team with all ten wickets in hand can attack far harder over 30 overs than over 50. Early rain rules that ignored this produced famous absurdities, including a 1992 World Cup semi-final in which a rain break turned a difficult chase into an impossible one: 22 runs needed off one ball.

The core idea: resources

DLS treats a batting side as holding a stock of resources, a combination of overs remaining and wickets in hand. A team starting a 50-over innings with ten wickets holds 100 percent of its resources. Every over used spends some; every wicket lost destroys some, and wickets destroy more when many overs remain. A table built from decades of match data says exactly what percentage any combination of overs and wickets is worth.

When rain shortens an innings, DLS compares the resources each side actually had available and scales the target so the chase is proportionally as hard as the original. If the second side ends up with fewer resources, the target comes down; if the first side's innings was cut short unexpectedly, denying it the late-innings acceleration it had saved wickets for, the target can go up, which is the case that most confuses viewers.

Par scores during a chase

During any interrupted-threat chase, broadcasters show a DLS par score: the total the chasing side needs to be ahead of, given wickets lost, if the match ended at that ball. If rain arrives and no further play is possible, the side ahead of par wins. This is why a chasing captain sometimes attacks recklessly with dark clouds approaching: being ahead of par when the rain comes is worth more than wickets in hand.

Why Stern, and what changed

The method began as Duckworth-Lewis in 1997, created by two English statisticians, and became DLS in 2015 when Australian academic Steven Stern updated it for modern scoring rates. The revision matters mostly in T20 and in very high-scoring matches, where the old resource tables underestimated how hard teams now finish an innings. The professional edition of the formula runs on software with match-specific inputs, which is why nobody computes it on paper in the stands.

Is it fair?

As fair as anything yet devised. DLS has flaws that analysts debate, it can favour chasing sides in T20, and it assumes typical scoring patterns that unusual pitches break, but every proposed replacement has failed to beat it on the cases that matter. Umpires, players and scorers accept it, which for a rain rule is the highest achievement available.

When rain arrives mid-match, our cricket live coverage shows the revised targets and par scores as they update, ball by ball.