The Resource Percentage Tables and the Target Calculation That Define the Duckworth-Lewis-Stern Method

The binding constraint of rain-affected cricket is that a team's ability to score runs depends entirely on two finite, depleting assets: the number of balls left to face, and the number of batters left to face them. If time and wickets are not treated as mathematically linked resources, any attempt to adjust a shortened target collapses into unfairness. In modern limited-overs cricket, this constraint holds absolute authority. The Duckworth-Lewis-Stern (DLS) method operates on this exact premise, translating the abstract momentum of a One Day International (ODI) or Twenty20 match into a hard percentage of remaining potential, ensuring that neither the batting nor the fielding side gains an unearned advantage from a sudden downpour.[1][2]

Before 1997, the sport relied on the Average Run Rate method, a system that fundamentally misunderstood how cricket is played. If a team batted first and scored 250 runs in 50 overs, their run rate was 5.0 per over. If rain reduced the chasing team's innings to 25 overs, the target was simply halved to 126. This proportional reduction ignored the reality of the sport: a team with all 10 wickets intact and only 25 overs to bat can attack with reckless aggression, knowing they do not need to preserve batters for a full 50-over innings. The old system effectively punished the team batting first for pacing their innings correctly.[1][4][5]

The breaking point arrived during the 1992 World Cup semi-final between England and South Africa. A brief rain delay resulted in South Africa's target being revised from 22 runs off 13 balls to an impossible 21 runs off a single delivery, effectively ending their tournament on a mathematical technicality. Watching the broadcast, British statisticians Frank Duckworth and Tony Lewis recognized that the existing formulas were mathematically broken. They set out to build a model that accounted for the exponential value of wickets in hand, eventually presenting their resource-based solution to the International Cricket Council (ICC).[4]

The genius of the methodology lies in its resource table. As the official ICC documentation states, "The D-L method sets revised targets in rain-interrupted limited-overs matches in accordance with the relative run scoring resources which are at the disposal of the two sides." The algorithm assigns a specific percentage value to every possible combination of overs remaining and wickets lost. At the start of a standard 50-over innings, a team possesses 100% of its resources. If a rain delay strikes before the second innings begins, reducing the chase to 30 overs, the chasing team does not lose 40% of its target. Because they still have all 10 wickets to deploy over a shorter period, the table dictates they retain 75.1% of their run-scoring resources.[1][5]

This resource premium fundamentally alters the math of a run chase. Using the 30-over scenario against a first-innings score of 240, a straight run-rate reduction would set the target at 144. The DLS method, however, multiplies the 240 runs by the 75.1% resource availability, generating a revised target of 181 runs. The algorithm mathematically forces the chasing team to score at a higher rate to compensate for the advantage of having a full roster of batters available for fewer deliveries, perfectly balancing the risk and reward of a shortened innings.[1][5]

The calculation becomes significantly more complex when rain interrupts play during an active innings. If a team is cruising at 150 for 2 after 30 overs and rain forces an abandonment, the DLS method calculates the resources they consumed before the stoppage. The algorithm determines the par score—the exact number of runs a team should have scored at that specific ball, given the wickets lost, to be on track for the target. If the batting team's actual score exceeds the par score, they win the match; if they fall short, the fielding side claims the victory.[2][5]

A critical feature of the system is how it penalizes early wickets. Losing a batter in the first five overs of a match depletes a massive chunk of a team's resource percentage, as that batter was expected to face dozens of deliveries. Conversely, losing a wicket in the 49th over barely registers on the resource table, as the batter's remaining utility was limited to a handful of balls. This mathematical weighting perfectly mirrors the strategic reality of limited-overs cricket, where preserving wickets for a late-innings assault is a foundational tactic.[1][2]

In 2014, Australian statistician Steven Stern took over the maintenance of the algorithm following the retirements of Duckworth and Lewis. Stern updated the underlying data to reflect modern scoring trends, specifically the explosive run rates generated in Twenty20 cricket and the final 10 overs of ODIs. The ICC officially renamed the system the Duckworth-Lewis-Stern method, acknowledging the refined mathematical model that now governs all international rain-affected matches and ensures the calculations remain accurate in an era of increasingly aggressive batting.[2][3][4][6]

Today, the DLS method exists in two formats. The Standard Edition, which relies on a publicly available resource table, is used in lower-level and recreational cricket. The Professional Edition, utilized in all international fixtures, is driven by a proprietary computer program that adjusts the resource percentages dynamically based on the first innings total. While the exact formula of the Professional Edition remains a closely guarded secret, the foundational logic—that runs require both time and batters to achieve—remains the undisputed law of the sport.[1][5][6]