Nothing frustrates cricket fans quite like rain. In Test cricket, bad weather usually means a draw and everyone goes home. But in ODIs and T20s, where a result is needed on the day, the game needs a fair way to adjust the target when overs are lost. That is the job of the Duckworth-Lewis-Stern method — DLS for short.
If you have ever watched a match stop for rain and heard commentators talk about "par score" and "resources," this guide explains what is really going on.
Before DLS: How Bad It Used to Be
Cricket's early attempts at rain rules were embarrassing. The most infamous example came in the 1992 World Cup semi-final between South Africa and England in Sydney. Rain interrupted South Africa's chase, and the rule in use — based on the "most productive overs" — recalculated their target from 22 runs needed off 13 balls to 22 runs needed off just 1 ball. An impossible task, a ruined semi-final, and a rule that was scrapped in disgrace.
Other early methods simply used run rate, which punished teams unfairly: a side cruising at 200/2 after 40 overs could lose to a side that had been struggling at 150/8, just because of when the rain arrived. Everyone agreed cricket needed something smarter.
Two Statisticians and a Simple Idea
In the 1990s, two English statisticians — Frank Duckworth and Tony Lewis — studied hundreds of one-day matches and noticed a pattern: a team's scoring potential depends on two resources, overs remaining and wickets in hand, and these two interact in predictable ways.
Their method was first used internationally in 1999 and quickly became the standard. In 2014, Australian statistician Steven Stern updated the calculations to reflect modern, higher-scoring cricket — faster scoring in the final overs, especially in T20s. The ICC renamed it the Duckworth-Lewis-Stern method in his honour.
The Core Idea: Cricket Is About Resources
DLS treats every innings as a pool of resources. A team starting a 50-over innings with all 10 wickets intact has 100% of its resources. As overs are used up or wickets fall, resources drain away — and wickets drain them faster than most fans realise.
This is the key insight: 30 overs remaining with 9 wickets in hand is worth far more than 30 overs remaining with only 3 wickets in hand. A team with wickets banked can accelerate; a team with few wickets left must play cautiously. Any fair rain rule has to account for this, and DLS does.
How a Revised Target Is Calculated
When rain shortens the second innings, officials compare the resources available to each team:
- Team 1 completes its innings (say, the full 50 overs — 100% resources used).
- Team 2's innings is interrupted, so their available resources are reduced (say, to 75%).
- Team 2's target is scaled by the ratio: 75/100 of Team 1's score, with adjustments.
The exact numbers come from official DLS tables and computer software used by match officials — nobody calculates them by hand at the ground. The principle, though, is simple: Team 2 is asked to score at the same scoring-resource rate that Team 1 achieved.
If the team batting first is also interrupted, the same logic applies in both directions — each side's target reflects only the resources they actually had.
What Is a "Par Score"?
During a rain break, you will hear about the "par score." This is the score the chasing team must have reached at that exact moment — given overs bowled and wickets lost — to be level with the opposition if no further play is possible. Score above par when rain ends the match, and you win; below par, you lose. That is why players and coaches watch the par score obsessively as dark clouds gather.
Why Wickets in Hand Matter So Much
Consider two teams chasing the same target, both 120/2 after 25 overs when rain arrives — versus a team that is 120/6 at the same stage. Under DLS, the team with eight wickets in hand has far more resources remaining than the team with four, so their par score is higher. It feels harsh if you are the team that lost early wickets, but it reflects a genuine cricketing truth: wickets in hand are scoring potential.
Criticisms and Limits
DLS is not perfect, and honest fans should know its limits. It was designed around 50-over patterns, and while Stern's update improved it for T20s, some analysts feel it still undervalues explosive late-order hitting in the shortest format. It also cannot measure momentum, pitch deterioration, or the quality of the specific batters at the crease — it deals in averages, not individuals.
Despite this, every serious study has found DLS fairer than the alternatives. It is the best system cricket has, and it is applied identically at every level, from World Cup finals to domestic leagues.
The Bottom Line
When rain arrives, DLS does not guess and does not favour either side — it converts overs and wickets into resources and sets a target both teams can respect. Next time play stops and the covers come on, you will know exactly what the officials are calculating, and why that par score number keeps flashing on your screen.