Duckworth-Lewis-Stern (DLS) Method Explained
Understand the DLS method in cricket: how it sets revised targets in rain-affected limited-overs matches, why it replaced simple run-rate calculations, and famous DLS controversies.
What is the DLS method?
The Duckworth-Lewis-Stern (DLS) method is the mathematical formula used to recalculate targets in limited-overs cricket matches interrupted by rain or other unforeseen delays. It is named after statisticians Frank Duckworth and Tony Lewis, who developed the original formula in the 1990s, and Professor Steven Stern, who took over custodianship and refined the model in 2014. DLS is the official ICC method for all international and most domestic limited-overs competitions.
Why was DLS needed?
Before DLS, rain-affected matches used crude methods that produced manifestly unfair results. The most infamous failure was the 1992 Cricket World Cup semi-final between England and South Africa: South Africa needed 22 runs off 13 balls when rain interrupted play. When play resumed with one ball remaining, the target was recalculated using the 'most productive overs' method — reducing England's total by their worst overs — giving South Africa an impossible target of 21 off 1 ball. The absurdity of that outcome drove the development of a better system. Duckworth and Lewis published their resource-based model in 1997 and it was adopted by the ICC in 1999.
How does DLS work?
DLS is based on the concept that a batting team has two resources to score runs: overs remaining and wickets in hand. Crucially, wickets are not equal to overs — a team with 10 wickets and 10 overs remaining has significantly more batting resource than a team with 3 wickets and 10 overs remaining. DLS uses a table of 'resource percentages' that captures how much of a team's expected scoring potential remains given any combination of overs and wickets. When overs are lost, the method calculates what proportion of total resources each team had available and scales the target accordingly. If the team batting second has fewer resources than the team batting first (due to rain), the DLS target is reduced. If the second team has more resources (e.g., rain falls during the first team's innings), the target is scaled up.
Famous DLS controversies
Despite being significantly more sophisticated than its predecessors, DLS has produced controversial outcomes. The 2019 Cricket World Cup semi-final between India and New Zealand at Old Trafford saw India given a DLS-revised target when rain interrupted their chase, which some felt did not fully account for the pitch conditions. In the 2007 World Cup final, Australia beat Sri Lanka under DLS when a brief shower altered the target — a match that Sri Lanka argued they were winning comfortably when play was interrupted. Critics note that DLS, like any statistical model, cannot fully account for pitch deterioration, dew, or changing conditions through the innings.
Frequently asked questions
Does DLS apply in T20 cricket?
Yes. DLS applies in T20I cricket and domestic T20 competitions. However, there is a minimum number of overs required for a T20 match to be valid — typically 5 overs per innings must be completed for a result to stand, though specific competitions may vary.
What does 'DLS par score' mean?
The DLS par score is the score the team batting second needs to have reached at a specific point in their innings for the match to be level on DLS calculations if rain stops play at that exact moment. If a match is abandoned mid-chase and the batting team is above the par score, they win; below par, they lose.
Who is responsible for applying DLS in a match?
The on-field umpires and match referee apply DLS using official ICC software or tables provided by the ICC. Teams' scorers assist in tracking the data. The third umpire may also be involved in confirming the precise over at which play stopped.