Simpson's Diversity Index Calculator

Find Simpson's diversity index for species counts.

Simpson's index (D) 0.7071

Formula: D = 1 − Σ[n(n−1)] ÷ [N(N−1)]

Step-by-step with your numbers:

1. Values used:

2. Species 1 count = 10

3. Species 2 count = 20

4. Species 3 count = 30

5. Species 4 count = 40

7. Simpson's index (D) = 0.7071

Did we solve your problem today?

Simpson's diversity index measures biodiversity, accounting for richness and evenness.

The math behind it

D = 1 − Σ[n(n−1)] ÷ [N(N−1)]. Higher D (closer to 1) means greater diversity.

Counts 10/20/30/40 → D ≈ 0.71.

What does D = 0 mean?

No diversity — every individual is the same species.