Enter the number of individuals of each species of up to 5 different species into the calculator to determine Simpson’s diversity index.

Simpson’s Diversity Index Formula

The following formula is used to calculate Simpson’s Diversity Index.

D = 1 – [ sum(n*(n-1) / N*(N-1) ]

  • Where D is the diversity index
  • n is the number of individuals of each species
  • N is the total number of individuals of all species

Simpson’s Diversity Index Definition

What is Simpson’s Diversity Index? Simpson’s diversity index, or sometimes just referred to as the diversity index, is a measure that outlines how many different types there are in a dataset that can take into account the phylogenetic relations among the individuals distributed amount those types. In other words, biodiversity in different aspects of species.

Example Problem

How to calculate Simpson’s Diversity Index?

  1. First, determine the number of individuals of each species.

    For this example, there are 5 different species with counts of 10,20,15,12,8.

  2. Next, determine the total number of individuals of all species.

    Adding together the numbers from step 1, we have a total of 65.

  3. Next, determine the sum of sum(n*(n-1)) of each individual species count.

    For this example, that would be 10*(9)+20*(19)+15*(14)+12*(11)+8*(7) = 868.

  4. Next, determine the value of N*(N-1) where N is the total number of individuals of all species calculated in step 2.

    N*(N-1) = 65*(65-1) = 4160.

  5. Finally, calculate the diversity index.

    Using the formula above, we find the diversity index to be D = 1 – (868/4160) = .7913.

About Simpson’s Diversity Index

What is richness? Richness quantifies the number of different types the dataset contains.

Simpson's diversity index calculator
simpson's diversity index formula