Simpson Diversity Index Calculator
Enter species names and their counts to instantly compute Simpson's D, 1-D, and the Reciprocal Index (1/D).
Species Counts
Add each species and the number of individuals observed.
| Species | Count (n) |
|---|
Results
Enter at least 2 species with counts to see results.
Simpson's D
—
Dominance
1 - D
—
Index of Diversity
1 / D
—
Reciprocal Index
Low diversity (D = 1)
High diversity (D = 0)
Total individuals (N):
—
Species richness (S):
—
Per-Species Breakdown
| Species | n | n(n-1) | Proportion |
|---|
Formula Reference
D = Σ ni(ni - 1) / N(N - 1)
Index of Diversity = 1 - D
Reciprocal Index = 1 / D
where ni = count of species i, N = total individuals.
Summary
Enter species names and their counts to instantly compute Simpson's D, 1-D, and the Reciprocal Index (1/D).
How it works
- Enter each species name and its individual count in the table.
- Add or remove rows as needed to represent your sample community.
- The calculator sums all individuals (N) and computes n(n-1) for each species.
- Simpson's D = sum of n(n-1) / N(N-1), where n is the count per species.
- The Index of Diversity (1-D) and Reciprocal Index (1/D) are derived automatically.
- 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
Last updated: 2026-07-01 ·
Reviewed by Nham Vu