How to use (3 steps)
- Select an example or enter a count table (labels and counts).
- Adjust Shannon log base or display options if needed.
- Shannon, Simpson, and (optional) Hill numbers/evenness are shown.
Diversity indices depend on sampling and preprocessing (filtering, normalization, etc.). Interpret results together with conditions.
Input (count table)
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Input mode
| label | count | Actions |
|---|
Paste (TSV/CSV)
Two columns: label, count (header optional).
Paste (TSV/CSV)
First column is label, remaining columns are samples (header recommended).
Display options
Results (Shannon & Simpson)
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Relative abundance (p)
Shannon contribution (−p ln p)
Top categories
| label | count | p |
|---|
Outputs
How it’s calculated
- Compute proportions p and calculate Shannon (−Σp ln p) and Simpson (Σp² etc.).
- Because “Simpson” varies by field, D/1−D/1/D are shown together.
- Hill numbers (q=0/1/2) and evenness can be shown as references.
When to use Shannon, Simpson, and Hill numbers
Use this page when you want one place to compare Shannon and Simpson without guessing which Simpson definition a paper used. It works for ecology datasets, classroom count tables, and any category-abundance list where you want richness and dominance summaries side by side.
Choose the sample layout first
Use single-sample mode when you are summarising one quadrat, trap, or classroom count table. Switch to multiple-sample mode when each column is a different site, treatment, or time point that should be compared with the same formula settings.
Read Shannon and Simpson together
Shannon is useful when you want sensitivity to rare categories, while Simpson is stronger when dominant categories drive the interpretation. Showing both helps you explain whether a change came from rare taxa, evenness, or one group taking over the dataset.
Next steps
FAQ
What is the difference between ln and log2 for Shannon?
Only the log base changes; rankings do not. Choose based on field conventions (default is ln).
Which one is the “Simpson index”?
Literature varies between D (Σp²), 1−D, and 1/D. This tool shows all three.
Is it okay to include zero counts?
Yes. They are treated as p=0 with zero contribution.
Can I compare samples?
Yes. Multi-sample (by columns) mode calculates indices for each column.
Are my inputs sent anywhere?
All calculations run in your browser. Your data is not sent.
Interpreting ecology and classroom datasets
Use the top-category table and the contribution chart together when you explain why two samples differ. A higher Shannon value can come from more evenness, while Simpson may still be dominated by one abundant category. That contrast is often exactly what a classroom discussion or ecology field note needs.
If your next question is about turnover between samples rather than within-sample diversity, move to beta diversity. If the next question is about stochastic change over generations, move to Wright-Fisher instead of forcing alpha-diversity indices to answer a population-drift problem.
Related tools
- Beta diversity calculator (Jaccard / Bray–Curtis) | CalcBECompare site-to-site turnover after you have finished alpha-diversity checks for each sample.
- Genetic drift simulator (Wright–Fisher)Move here when the next question is generational drift or allele-frequency change instead of within-sample richness.
- BiologyBrowse related biology calculators for ecology, genetics, qPCR, and classroom data workflows.
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