The short answer
When rain or bad light shortens a limited-overs cricket match, the Duckworth-Lewis-Stern (DLS) method decides the target or the result. It is based on one idea: a team's run-scoring potential depends on two resources:
- Overs remaining, and
- Wickets in hand.
DLS calculates what share of their total resources each team had. If the team batting second has fewer resources than the team batting first, their target is reduced, in proportion. If they have more, it can be increased.
DLS is used in One Day Internationals (ODIs) and T20 internationals, and in most professional limited-overs leagues.
Why simple averages do not work
Before DLS, rain rules used simpler methods, such as the run rate. These were often unfair. The most famous example is the 1992 World Cup semi-final between England and South Africa, when a rain break left South Africa needing an impossible 21 runs from one ball under the rule then used.
The flaw was that a run rate ignores wickets. A team with 10 wickets in hand and 10 overs left can attack far harder than one with 2 wickets left. DLS accounts for both.
What "resources" means
Think of a team's innings as 100 percent of its resources at the start: all overs and all wickets.
- As overs are used, resources fall.
- As wickets fall, resources fall, and they fall faster later in the innings.
- Losing overs to rain takes away resources too.
The DLS tables (and software used by match officials) give the percentage of resources remaining for any combination of overs left and wickets lost. They are derived from statistical analysis of thousands of matches and are updated periodically.
A simple illustration
These numbers are rounded and illustrative, to show the logic rather than an official calculation.
The situation: Team A bats first and scores 250 in their full 50 overs, using 100 percent of their resources. Rain then shortens Team B's innings so that, by the DLS tables, Team B will have only 80 percent of the resources Team A had.
The calculation: Team B's par score = 250 × 80% = 200. To win, Team B needs one more run than par: a target of 201.
When the second team has more resources: in ODIs, if Team A's innings was cut short by rain while Team B gets a full innings, Team B may end up with more resources. Then the target is increased, using an average score figure, rather than a simple percentage of Team A's score.
In real matches, officials use the official DLS software, which handles every interruption, at any point, for either team.
Par scores during a chase
The par score is the score the chasing team needs at a given point, for the wickets they have lost, to be exactly level. Scoreboards and broadcasts often show it during rain-threatened chases.
- Above par when play stops for good: the chasing team wins.
- Below par: the chasing team loses.
- Exactly on par: the match is a tie.
Because wickets count, a chasing team can be ahead on runs but behind on DLS if they have lost several wickets. That is why captains in rain-threatened games watch the par score closely and adjust their batting.
Minimum overs for a result
For DLS to decide a match, each team usually needs to have faced a minimum number of overs, unless one side has already been bowled out or the target reached:
- ODIs: 20 overs per side.
- T20 internationals: 5 overs per side.
Competitions can set their own rules, so check the playing conditions for a particular tournament. If the minimum is not reached, the match is usually declared a no result.
Why DLS sometimes feels unfair
DLS is widely accepted as the fairest available method, but it has critics:
- It is hard to follow. Fans and even players cannot easily calculate targets.
- Modern scoring is faster. T20 cricket and aggressive ODI batting have changed how resources are used. The method's tables are periodically updated to reflect this.
- Context matters. DLS does not know about pitch conditions, a dangerous batter at the crease, or dew.
- Alternatives exist. The VJD method, devised by Indian engineer V. Jayadevan, has been used in some Indian domestic cricket.
Key takeaways
- DLS resets targets in rain-affected matches by comparing each team's resources: overs and wickets.
- The chasing team's target is scaled to the share of resources they get.
- The par score shows whether a chasing team is ahead or behind at any moment.
- ODIs usually need 20 overs per side for a result, and T20Is need 5.
For upcoming tournaments, see our cricket World Cup preview and PSL vs IPL comparison.