The Duckworth-Lewis-Stern Method Explained

The Duckworth-Lewis-Stern method (DLS) is the mathematical system cricket uses to set a fair target when rain or bad light shortens a limited-overs match. Instead of simply cutting the target in line with the overs lost, Duckworth Lewis Stern looks at the two things a batting side actually has to work with, overs and wickets, and adjusts the target so both teams are judged on the share of those “resources” they had available.

That is the whole idea in one line. The rest of this guide explains how the resources work, why the method replaced the older rain rules, how par scores are read during a match, and why DLS still causes arguments in press boxes every season.

Key facts

• DLS is used in rain-affected one-day internationals, T20 internationals and almost every professional limited-overs league, from the IPL to The Hundred.
• It was devised by English statisticians Frank Duckworth and Tony Lewis, first used in international cricket in 1997, and renamed in 2014 after Australian academic Steven Stern took over as its custodian.
• A team’s “resources” are the combination of overs remaining and wickets in hand. Losing wickets reduces resources just as losing overs does.
• The revised target is the par score plus one. Matching the par score exactly means a tie.
• In ODIs each side normally has to face at least 20 overs for a result, and in T20Is at least five overs, unless the playing conditions for a specific event say otherwise.

What problem does the Duckworth-Lewis-Stern method solve?

Imagine a side batting second in a 50-over game, chasing 250. Rain arrives and the chase is cut to 25 overs. The lazy answer is to halve the target to 125. But that is hopelessly generous to the chasing side, because they still have all ten wickets for only 25 overs. They can swing from the first ball in a way the side batting first could not.

Before Duckworth and Lewis, cricket tried several fixes and none of them worked well. The simple average run rate method rewarded the chasing side in exactly the way described above. The “most productive overs” method, used at the 1992 World Cup, went the other way and could be brutal on the chasing side.

The 1992 World Cup semi-final

The most famous rain-rule disaster happened at the Sydney Cricket Ground in the 1992 semi-final between England and South Africa. South Africa needed 22 from 13 balls when a short shower stopped play. Under the most productive overs rule, the overs lost were removed along with very few runs, and when the players came back the target left South Africa needing 21 from one ball. It was a nonsensical finish to a fine game, and it convinced plenty of people that cricket needed something better.

Frank Duckworth, a statistician, and Tony Lewis, a mathematics lecturer, took up the challenge. Their method was first used in an international in Harare on New Year’s Day 1997, when Zimbabwe beat England, and it was used at the 1999 World Cup before becoming the ICC’s standard method.

How Duckworth Lewis Stern works: the idea of resources

The heart of the method is a simple observation. A batting side’s ability to score runs depends on two things: how many overs it has left and how many wickets it has left. Take away overs and the side can’t score as many. Take away wickets and the side has to bat more carefully, so it also can’t score as many.

DLS expresses this as a percentage. At the start of a 50-over innings, with ten wickets in hand, a team has 100% of its resources. As the innings goes on, that percentage falls. Losing early wickets makes it fall faster, because the batting side then has to be more cautious with the overs still to come.

Why wickets matter so much

This is what separates DLS from the old methods. Picture two sides that are both 120 after 25 overs. One is 120 for 1, the other 120 for 7. Under a run-rate rule, they are in identical positions. Under DLS, the side on 120 for 1 is far better placed, because it still has the batting to accelerate. If rain ends the game at that point, the chasing side that kept its wickets is much more likely to be ahead on par.

The resource figures come from a large body of real scoring data. Duckworth and Lewis studied how runs are typically scored across an innings, and the tables have been recalibrated since, most notably when Stern updated the model to reflect how much more aggressively modern teams bat in the closing overs.

A rough guide to the resource table

The table below shows approximate resources remaining at different points with all ten wickets in hand, based on the published Standard Edition. The exact figures used in professional cricket come from software and differ slightly, so treat these as illustrations rather than official numbers.

Overs left	Approx. resources remaining (10 wickets in hand)	What it tells you
50	100%	A full innings, nothing used yet
40	About 89%	Losing 10 overs costs only about 11% of resources
30	About 75%	Overs are worth more as the innings shortens
20	About 57%	Losing 30 of the 50 overs still leaves over half the resources
10	About 32%	With wickets in hand, short innings are run-rich

Notice the pattern. Twenty overs is 40% of a 50-over innings, but with all ten wickets it is worth more than half of the resources. That is exactly why the chasing side in our earlier example should not get its target halved.

How the revised target is calculated

Once you understand resources, the calculation is easier than its reputation suggests. There are two broad situations.

When the side batting second loses overs

This is the most common scenario. If the chasing side ends up with fewer resources than the side that batted first, its target is scaled down in proportion. The formula is: Team 1’s score multiplied by (Team 2’s resources divided by Team 1’s resources). The answer, rounded down, is the par score, and the target is par plus one.

So if Team 1 made 250 using 100% of its resources and Team 2 will have 70% because of a delay, par is 250 × 0.70 = 175, and the target is 176.

When the side batting first loses overs

This is trickier, and it is where DLS is cleverest. Suppose Team 1 is cruising along and then rain cuts its innings short without warning. It batted for, say, 40 overs while expecting 50, so it paced its innings for 50 and never got to launch at the end. Team 2, meanwhile, knows from ball one that it has 40 overs.

In that case, Team 2 actually has more resources than Team 1 had, because Team 1 lost the overs at the death that it was saving its wickets for. DLS responds by increasing the target above Team 1’s actual score. Fans sometimes find this baffling (how can you need more runs than the other side scored?), but it is the fairest outcome. Team 1 was robbed of its final assault, and the target compensates for that.

Standard Edition and Professional Edition

There are two versions. The Standard Edition uses a published table and a fixed formula, and it is the one you can work out with a calculator in a club pavilion. The Professional Edition, used in international and top professional cricket since the early 2000s, runs on software and better reflects very high-scoring games, where the relationship between resources and runs is not perfectly straight. That is why your own back-of-an-envelope sums on TV sometimes disagree with the official target by a few runs.

Reading the par score during a match

When rain is in the air, broadcasters put up a DLS par score. This is the score the chasing side needs at that exact moment, for its current number of wickets, to be level if no more cricket is possible. It changes with every ball and every wicket.

That is why captains and analysts watch it so closely. A batting side ahead of par when dark clouds roll in will often stop taking risks, because a wicket could drop them below par in an instant. A bowling side behind par will chase wickets, since one dismissal can swing the par score by 15 or 20 runs.

The 2003 World Cup lesson

The most painful example of misreading par came at the 2003 World Cup in Durban. South Africa, the hosts, needed to beat Sri Lanka to stay in the tournament. With rain coming, the dressing room passed a message to Mark Boucher about the score they needed. Boucher hit a six, then blocked the last ball of the over believing they were ahead. They weren’t. The figure they had been working from was the score to tie, not to win. The match ended level on DLS and South Africa went out of their own World Cup.

The lesson stuck. Teams now keep an analyst on top of the par score at all times, and you will often see a substitute running out with a note when rain threatens.

Where DLS is used and the minimum overs rule

DLS applies to limited-overs cricket only. Test matches have no need for it, because there is no target set in overs, and a rain-hit Test simply ends in a draw if time runs out. You can read more about how Test results feed into the bigger picture in our guide to the World Test Championship.

For a limited-overs match to produce a DLS result, both teams must have had the chance to face a minimum number of overs. Under standard ICC playing conditions that is 20 overs per side in ODIs and five overs per side in T20 internationals. Competitions can set their own minimums, and knockout games at major tournaments often require more cricket before a result can stand, with reserve days added for important fixtures.

If the minimum can’t be reached, the match is abandoned as a no result. In a franchise league or a group stage, that usually means a point each. For the current wording of ICC rules on shortened matches, the ICC playing conditions are the official reference.

T20 cricket and DLS

DLS was built for 50-over cricket, so how well it fits T20 is a fair question. In a T20 innings, wickets matter less because there are so few overs to use them in, and teams attack from the first ball. Stern’s updates aimed partly at these high-scoring formats. Most experts accept DLS still works reasonably in T20, though short rain-reduced games (five or six overs a side) remain something of a lottery whatever system you use.

It has decided plenty of T20 games in leagues like the IPL. If you follow the tournament closely, our IPL winners list covers every final, including seasons where the weather had its say.

A worked example, step by step

Here is a simplified, illustrative example using rounded figures. Real targets are calculated by official software, so the numbers would differ a little in a professional game.

1. Team A bats first and makes 280 in their full 50 overs. They used 100% of their resources.
2. Rain arrives during the break. Team B’s innings is cut to 30 overs before it begins.
3. With 30 overs and ten wickets, Team B has roughly 75% of the resources of a full innings.
4. Par = 280 × 0.75 = 210. The revised target is 211 from 30 overs.
5. That requires about seven an over, compared with 5.6 an over in the original chase. It feels tougher, and it should, because Team B has fewer overs to spend its ten wickets on.

Now a second scenario. Team B starts the full 50-over chase, and rain stops play at 150 for 2 after 30 overs. If no further play is possible, Team B wins if it is ahead of the DLS par score for 30 overs with two wickets down. If it had been 150 for 6 instead, par would be much higher, and Team B might well be behind. Same runs, very different position.

The men behind the method

Frank Duckworth was a statistician who worked in nuclear energy research, and Tony Lewis lectured in mathematics. Neither was a cricket insider, which may be why they approached the problem so cleanly. Their method became so standard that “Duckworth-Lewis” turned into everyday cricket vocabulary, used in commentary boxes around the world.

Lewis died in 2020 and Duckworth in 2024. By then the method had passed to Steven Stern, an Australian statistician, who updated it to cope with modern scoring rates. In 2014 the ICC added his name, and the system became the Duckworth-Lewis-Stern method.

Common myths and mistakes about DLS

Because the calculations happen out of sight, DLS attracts a lot of half-truths. Here are the most common ones.

“It just reduces the target by the overs lost”

No. That was the old average run rate method. DLS deliberately avoids a straight pro-rata cut because wickets in hand make a shorter chase easier per over.

“The target can never be higher than the first innings score”

It can, when the side batting first is interrupted and loses its final overs. In that case the chasing side has more resources than its opponents did, so the target goes up.

“The par score is the target”

This is the Durban 2003 mistake. Par is the score for a tie. The target is par plus one. If you are exactly on par when the game ends, it is a tie, not a win.

“DLS favours the side batting second”

There is no built-in bias either way. It is true that some captains prefer to chase when rain is forecast because they will know the target and can manage the par score, but that is a tactical advantage of information, not a flaw in the maths.

“It’s the same in every competition”

The method is the same, but minimum overs, reserve days and cut-off times vary between events. Always check the tournament’s own playing conditions.

Criticisms and alternatives

DLS isn’t perfect, and nobody involved claims it is. The most common complaint is that it can be harsh on bowling sides in very short games, where ten wickets across five overs makes almost any target gettable. Others argue it underrates how modern T20 batters treat wickets as cheap.

The best-known rival is the VJD method, developed by Indian engineer V Jayadevan. It has been used in some domestic cricket in India, and its supporters say it handles the pattern of acceleration in an innings more realistically. The ICC has reviewed alternatives over the years and kept DLS as the international standard.

The practical case for DLS is simple. Players, umpires and broadcasters understand how to use it, the par score gives everyone a live reference point, and it hasn’t produced anything like the farce of Sydney 1992.

Frequently asked questions

What does DLS stand for in cricket?

DLS stands for Duckworth-Lewis-Stern, named after Frank Duckworth, Tony Lewis and Steven Stern. It is the method for setting revised targets in rain-affected limited-overs matches.

Is DLS used in Test cricket?

No. Test matches are not played to a fixed number of overs per innings, so there is nothing for DLS to adjust. If weather stops a Test from finishing, it is usually a draw.

Why did the target go up after rain?

If the side batting first loses overs unexpectedly, it never gets to use the wickets it saved for the final overs. The chasing side, who knows its overs in advance, therefore has more resources, so DLS raises the target to keep things fair.

What is the difference between par score and target?

Par is the score that would leave the match tied if no more play is possible. The target is par plus one, the score the chasing side needs to win.

How many overs are needed for a DLS result?

Under standard ICC playing conditions, each side must face at least 20 overs in an ODI and five overs in a T20 international. Individual tournaments can set higher minimums, particularly for knockout matches.

Can fans calculate DLS targets themselves?

You can get close using the published Standard Edition table, which is a good way to understand the method. Professional matches use the Professional Edition software, so official targets can differ by a few runs from home calculations.

Rain has shaped some of the greatest finishes in limited-overs history, and so have the tightest finishes with no weather at all. For a reminder of how close one-day cricket can get, relive the 1999 World Cup semi-final tie between Australia and South Africa, or browse the Cricket World Cup winners list to see how every tournament ended.