Ecology & populations · SL/HL
Lincoln Index Population Calculator
Enter the first marked sample, total second capture and marked individuals recaptured.
Your values
Start with the example or enter your own values. Use a dot for decimals and e for scientific notation.
Calculated locally. No account or input upload.
Result & working
ExampleThe calculator is loading. The worked example is also shown below.
Step-by-step working
The formula
estimated population N = n₁n₂/n₃
| Symbol | Meaning |
|---|---|
| n₁ | Number initially captured and marked. |
| n₂ | Total caught on the second occasion. |
| n₃ | Marked individuals in the second capture. |
When to use this calculator
The estimate depends on assumptions such as marks remaining identifiable, sufficient mixing, and similar capture probability.
Worked example
The page opens with these example values. The result below is pre-generated for reference.
- N = n₁n₂/n₃ = 80 × 70 / 14 = 400
Estimated N = 400
Common mistakes
- If no marked individuals are recaptured, the simple Lincoln estimate is undefined.