Lincoln Index Calculator
🌍 Ecology. Use the Lincoln index (mark–release–recapture) formula to find estimated population, first catch (marked), second catch, marked in the second catch: pick the value you want, type the others, and the answer updates as you go.
n₁ caught and marked; n₂ caught later; m of those were marked.
Pick the ○ next to the value you want to find, fill in the others, and it solves as you type.
What each letter means
| Quantity | Unit |
|---|---|
| Estimated population | no unit |
| First catch (marked) | no unit |
| Second catch | no unit |
| Marked in the second catch | no unit |
Worked example
Find the estimated population when First catch (marked) = 40, Second catch = 50, Marked in the second catch = 10.
Using N = (n1 × n2)/m: Estimated population = 200.
Frequently asked questions
What is the formula for Lincoln index (mark–release–recapture)?
N = (n1 × n2)/m. n₁ caught and marked; n₂ caught later; m of those were marked.
What do the letters stand for, and what units are used?
Estimated population, First catch (marked), Second catch, Marked in the second catch.
How do you calculate estimated population?
Put the values into N = (n1 × n2)/m. For example, with First catch (marked) = 40, Second catch = 50, Marked in the second catch = 10, estimated population = 200.
Can I solve for a different value?
Yes. In the calculator above, pick the circle next to any value (estimated population, first catch (marked), second catch, marked in the second catch) and fill in the others: it rearranges the formula for you.
