The DLS Method Explained: How Rain Actually Decides Cricket Matches

A match is interrupted by rain. Play resumes. A number appears on the screen that nobody in the crowd expected, and half of them are certain their team has been robbed.

The Duckworth-Lewis-Stern method is the most misunderstood thing in cricket, and almost all of the misunderstanding comes from one wrong assumption: that it works on run rates. It does not. Once you understand what it actually measures, the numbers stop looking arbitrary.

The core idea: two resources, not one

At the start of an innings a batting side has two things:

1. Overs remaining
2. Wickets in hand

DLS treats these as a single combined quantity called resources, expressed as a percentage. At the start of a 50-over innings with ten wickets standing, a team has 100% of its resources.

Every ball bowled consumes some. Every wicket lost consumes considerably more.

That second point is the entire method. A run-rate calculation treats a team at 200/1 and a team at 200/9 as identical after 30 overs. Anyone who has watched cricket knows they are not remotely identical — one can accelerate freely, the other cannot bat at all. DLS is the maths that encodes that obvious truth.

Why wickets matter so much

Consider two teams, both 150 after 30 overs of a 50-over match.

Team A: 150/1. Twenty overs left, nine wickets in hand. They can throw everything at it and might well finish on 340.

Team B: 150/8. Twenty overs left, two wickets in hand. They will be lucky to reach 200 and are more likely to be bowled out inside ten overs.

If rain ends both innings there, a run-rate method would call them equal. DLS says Team A has far more resources left unused, and therefore had far more of its innings taken away by the weather. Their revised target or par score reflects that.

This is why a side that loses early wickets often finds DLS unhelpful to them — they have already spent the resource that matters most.

Reading a par score

During a rain-affected chase you will see a par score on screen. It means: if the match were abandoned right now, this is the score the chasing side needs to have exceeded to win.

Two things confuse people about it.

It jumps when a wicket falls. Losing a wicket consumes a chunk of resources, so the par score the batting side must beat rises immediately. That is not the system punishing them; it is the system recognising that their capacity to score just fell.

Being level is a tie, not a win. You must be ahead of par. A side exactly level when rain ends the match has tied.

The two ways DLS is used

Overs lost before or during the first innings — the target for the second innings is adjusted upward or downward to reflect the resources each side actually had. If the team batting first lost overs, the chasing side gets a target higher than the runs actually scored, because the chasing side knows from ball one that it has a shorter innings and can bat accordingly. That adjustment is the source of most “why is the target higher than their score?” complaints, and it is correct.

Overs lost during the second innings — the target is revised down to match the reduced resources available.

Why chasing sides sometimes seem to benefit

A common complaint: rain interruptions favour the team batting second. There is a grain of truth in it, and it has nothing to do with the maths being wrong.

A team batting first does not know an interruption is coming. It paces a 50-over innings, holds wickets back for a finish that never arrives, and finds its innings guillotined at 35 overs with resources unspent.

A team batting second, resuming after rain with a revised target of, say, 180 from 25 overs, knows exactly what it needs from ball one and can plan the whole chase. Certainty is worth something, and DLS cannot compensate for information the first side never had.

The professional edition of DLS makes adjustments that reduce this effect, but it cannot eliminate it. It is a limitation of the situation, not an error in the formula.

What “Stern” added

The method began as Duckworth-Lewis in 1997, developed by statisticians Frank Duckworth and Tony Lewis. Steven Stern took over as custodian in 2014, and the name changed to reflect it.

The substantive change was recalibration for modern scoring. Duckworth-Lewis was built on data from an era when 250 was a strong ODI total. By the 2010s teams were routinely making 350 and chasing 300 without alarm. The resource tables were re-fitted so that high-scoring games are handled properly rather than treated as statistical outliers.

There is also a professional edition used in international and top-tier cricket that handles very high first-innings totals more accurately, and a standard edition used at lower levels where the full computation is impractical.

The T20 problem

DLS works less well in T20 than in ODIs, and the reason is structural rather than mathematical.

Twenty overs is a short innings with much less variation in how resources get spent — almost every side attacks from the start, so the “wickets in hand allow acceleration” relationship that DLS is built on is compressed. Five overs is a quarter of a T20 innings and a tenth of an ODI innings, so each interruption is proportionally far more disruptive.

The method still applies and is still the best available answer. It is simply operating with less room.

The five-over minimum

For a T20 international to produce a DLS result, the side batting second generally needs to have faced a minimum number of overs — five in most competitions. Below that, there is not enough of an innings to calculate anything meaningful and the match is a no result.

In ODIs the equivalent threshold is twenty overs. This is why you occasionally see a match abandoned with a chasing team apparently well ahead: they had not batted long enough for the result to count.

The honest summary

DLS is not perfect and nobody claims it is. It cannot restore the information a first-innings side lost, it strains in T20, and it will always produce occasional outcomes that feel wrong in the moment.

What it does do is convert an unfair situation into a defensible one, using a model built on decades of actual scoring data rather than on the run-rate arithmetic that everyone’s intuition reaches for first. Before it existed, rain-affected matches were settled by methods that produced genuinely absurd results — most infamously the 1992 World Cup semi-final, where South Africa’s target went from 22 off 13 balls to 22 off 1 ball after a twelve-minute rain break.

Compared to that, a par score that jumps when a wicket falls is not the problem. It is the fix.

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