Species Diversity Calculator Formula

Understand the math behind the species diversity calculator. Each variable explained with a worked example.

Use the Species Diversity Calculator

Formulas Used

Shannon Diversity Index

diversity_index = shannon_index

Maximum Possible H'

max_h = max_diversity

Evenness (J)

evenness_out = evenness

Average per Species

avg_per_species = total_individuals / num_species

Variables

VariableDescriptionDefault
num_speciesNumber of Species10
total_individualsTotal Individuals200
evennessDistribution Evenness(0-1)0.8
max_diversityDerived value= log(num_species)calculated
shannon_indexDerived value= log(num_species) * evennesscalculated

How It Works

How to Calculate Species Diversity

The Shannon Diversity Index (H') measures both species richness and evenness of distribution.

Formula

H' = -Sum(pi * ln(pi)) for each species

Simplified: H' = ln(S) * J

Where S = number of species, J = evenness (0-1)

Interpretation

  • H' < 1: Low diversity
  • H' = 1.5-3.5: Moderate diversity
  • H' > 3.5: High diversity

    • Worked Example

    A habitat with 10 species, 200 total individuals, and 0.8 evenness.

    num_species = 10total_individuals = 200evenness = 0.8
    1. 01Max diversity: ln(10) = 2.303
    2. 02Shannon index: 2.303 * 0.8 = 1.842
    3. 03Average per species: 200 / 10 = 20 individuals
    4. 04This indicates moderate diversity

    Ready to run the numbers?

    Open Species Diversity Calculator