About the Duckworth-Lewis method
The Duckworth-Lewis method (formally the Duckworth-Lewis-Stern, or DLS, method) is the standard way to reset a fair target in a limited-overs cricket match that is shortened by rain or another interruption. It was devised by English statisticians Frank Duckworth and Tony Lewis, adopted by the International Cricket Council in 1999, and later refined by Steven Stern. Its central idea is that a batting side has two resources to make runs: the overs still to be bowled and the wickets still in hand. When an interruption takes overs away, it removes some of those resources, and the target is adjusted in proportion.
The formula
Every point in an innings is expressed as a resource percentage, read from a published two-way table of overs remaining against wickets lost. A full, uninterrupted 50-over innings with all ten wickets in hand equals 100%. Let R1 be the resource percentage available to the team batting first and R2 the resource percentage available to the team batting second. If Team 1 scored S runs, the par score for Team 2 is:
- If R2 ≤ R1 (Team 2 has the same or fewer resources):
Par = S × (R2 / R1) - If R2 > R1 (Team 2 has more resources, e.g. Team 1's innings was cut short):
Par = S + G50 × (R2 − R1) / 100
Here G50 is the average total a team is expected to score from a full 50 overs; the ICC Standard Edition uses 245 for men's internationals. The par score is the total Team 2 must reach to tie. To win, Team 2 needs the par score rounded down plus one run.
Why the two cases exist
When Team 2 has fewer resources than Team 1, scaling the score down by the resource ratio is enough. But when Team 2 has more resources than Team 1 — most often because Team 1's own innings was interrupted and shortened — simply multiplying would unfairly inflate the target. The G50 term instead adds runs at the average scoring rate for the extra resources, so the target rises realistically rather than explosively.
A worked example
Suppose Team 1 posts 250 from a full innings, so R1 = 100%. Rain then reduces Team 2's chase so that it has only R2 = 75% of resources. Because R2 ≤ R1, par = 250 × (75 / 100) = 187.5. Rounded down that is 187, so Team 2 needs 188 to win and 187 would tie. Now suppose instead Team 1's innings was cut so it used only R1 = 80%, still scoring 250, while Team 2 gets R2 = 90%. Because R2 > R1, par = 250 + 245 × (90 − 80) / 100 = 250 + 24.5 = 274.5, so Team 2 needs 275 to win.
Where the resource percentages come from
This calculator takes R1 and R2 as inputs so it works with any edition of the tables. In a live match those figures are looked up from the official DLS resource table using the exact overs remaining and wickets lost at each interruption; broadcasters and match officials use ICC-licensed software for the current Professional Edition. Common reference points on the Standard Edition table: 50 overs and 0 wickets down = 100%; 25 overs and 0 down ≈ 66.5%; 10 overs and 0 down ≈ 34.1%; and 20 overs with 5 wickets down ≈ 42.2%.