Simpson Diversity Index Calculator

Summary

Simpson's Diversity Index (D) is a widely used measure in ecology that quantifies species diversity in a community. It accounts for both species richness (the number of different species) and evenness (how evenly individuals are distributed among species). A value of D near 0 indicates high diversity, while D near 1 indicates low diversity — a community dominated by a single species.

How it works

1. Enter each species name and its individual count in the table.
2. Add or remove rows as needed to represent your sample community.
3. The calculator sums all individuals (N) and computes n(n-1) for each species.
4. Simpson's D = sum of n(n-1) / N(N-1), where n is the count per species.
5. The Index of Diversity (1-D) and Reciprocal Index (1/D) are derived automatically.
6. Results update instantly as you type.

Use cases

• Ecology fieldwork: quantify species diversity from transect or quadrat surveys.
• Classroom exercises on biodiversity and community ecology.
• Environmental impact assessments comparing pre- and post-intervention communities.
• Comparing diversity between habitats, seasons, or treatment groups.
• Freshwater, marine, and terrestrial biodiversity monitoring.
• Microbiome studies using OTU or ASV count data.
• Reporting biodiversity metrics for conservation planning.
• Quickly checking Simpson's D against textbook examples.

Frequently Asked Questions