When rain cuts a limited-overs match short, someone has to decide what the chasing team now needs. Since 1997 international cricket has used the Duckworth-Lewis method, renamed Duckworth-Lewis-Stern (DLS) in 2014. This calculator applies the published Standard Edition arithmetic to the resource percentages you enter, and gives you the revised target and par score. It is a learning and estimating tool: official international targets come from the ICC's DLS Professional Edition software, which is not public, so real targets can differ.
The big idea: resources, not overs
Earlier rain rules looked only at overs. DLS recognises that a team's chances depend on two things: overs remaining and wickets in hand. Together these are called resources. At the start of a 50-over innings with all ten wickets, a team has 100% of its resources. As overs pass and wickets fall, resources are used up. If rain takes away overs, the team loses the resources those overs would have provided.
DLS compares the resources each team had (R1 for the side batting first, R2 for the chasing side) and adjusts the target in proportion.
How to use the DLS calculator
- Enter Team 1's score (S).
- Enter R1, the resources Team 1 used. For an uninterrupted 50-over first innings this is 100.
- Enter R2, the resources Team 2 has available after the interruption.
- Leave G50 at its default unless your competition uses a different value. It only matters when R2 is larger than R1.
- Read the revised target, the par score (which ties the match) and which rule was applied.
The Standard Edition formulas
If R2 is less than or equal to R1: Par = S × R2 ÷ R1
If R2 is greater than R1: Par = S + G50 × (R2 − R1) ÷ 100
The par score is rounded down to a whole number, and the target to win is par + 1. If the chasing team finishes exactly on the whole-number par, the match is tied.
G50 is the average score expected from an uninterrupted 50-over innings. It is used when Team 2 has more resources than Team 1, typically because Team 1's innings was interrupted, so that Team 2's extra resources are converted into extra runs rather than a simple ratio.
Resource percentages at the start of an innings
These values come from the ICC's published Duckworth-Lewis Standard Edition table, for an innings that has lost no wickets:
| Overs available | Resources (0 wickets lost) |
|---|---|
| 50 | 100.0% |
| 40 | 89.3% |
| 30 | 75.1% |
| 20 | 56.6% |
| 10 | 32.1% |
Notice that 20 overs is 40% of a 50-over innings, but it provides 56.6% of the resources. A team with all ten wickets and only 20 overs can bat much more aggressively than one facing 50, which is exactly what the old run-rate rules missed.
Worked example
Chasing 251, cut to 30 overs before the chase starts
- R2 (30 overs, 0 wickets lost)
- 75.1%
- Par = 250 × 75.1 ÷ 100
- 187.75 → 187
- Target to win
- 188 in 30 overs
- Required rate
- 6.27 per over
A straight run-rate method would set the target at 151 (5.00 an over for 30 overs), much easier because it ignores the ten wickets Team 2 still has.
An interruption during the chase
Suppose Team 2 is 2 wickets down with 40 overs left when rain arrives, and play resumes with 30 overs left, still 2 down. From the Standard Edition table, 40 overs with 2 wickets lost is 84.2%, and 30 overs with 2 wickets lost is 71.8%. The rain cost 84.2 − 71.8 = 12.4% of resources, so R2 = 100 − 12.4 = 87.6%. With Team 1 on 250, par is 250 × 0.876 = 219, and the target becomes 220 in a reduced 40-over chase.
Standard Edition versus Professional Edition
- Standard Edition uses a single published table and simple arithmetic. It can be worked out by hand and is still used in some domestic and recreational cricket.
- Professional Edition is run on computer software by match officials in international and major professional cricket. It adjusts resources for high-scoring matches and has been updated using modern data, so it does not reduce to a single table. That is why this calculator's targets are estimates for international games.
Common mistakes
- Using overs instead of resources. Halving the overs does not halve the target.
- Forgetting wickets. Resources at an interruption depend on wickets lost at that moment.
- Mixing up par and target. Par ties the match; par + 1 wins it.
Compare DLS with the simpler Average Run Rate method, and use the required run rate calculator once the revised target is set. The full methodology is published in the ICC Duckworth-Lewis methodology document.
