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Species Richness and Shannon Diversity Calculator

Calculate observed richness, Shannon diversity, effective species number and Pielou evenness from a pasted list of species counts.

Use this result well

Inputs that matter
Species counts (one per line)
Output to expect
Species Richness and Shannon Diversity
  • Check the units and required inputs before comparing results.
  • Keep the assumptions with a copied result so you can reproduce the calculation later.
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Reference & details

How it works

Richness and Shannon diversity

Only positive counts contribute to observed richness S. Divide each count by the total to obtain its proportion; Shannon H is the negative sum of p × ln(p), using natural logarithms.

Source: vegan — Ecological Diversity Indices

Effective species and evenness

The exponential of H expresses diversity as an effective number of equally abundant species. Pielou J divides H by ln(S); it is undefined for a sample with only one observed species.

Source: abdiv — Shannon Diversity and Related Measures

Input contract

Use nonnegative whole-number counts for distinct species in one sample. Zero rows are permitted but do not increase richness. An empty or all-zero sample has no computed diversity. Counts and their total must fit JavaScript’s exact integer range.

Updated: September 2026

Example Scenarios

Calculate observed richness and abundance-weighted diversity from the counts in your field record.

Compare an even distribution with a sample dominated by one species, while keeping the interpretation tied to the entered data.

Common Mistakes to Avoid

Counting the same species in multiple rows

Combine its counts before entering the list; each positive row is counted as a distinct species.

Treating H as a universal habitat-quality grade

Interpret alongside survey design, effort, identification and ecological context. No high/medium/low label is assigned.

Pasting names, percentages or comma-formatted numbers

Paste one plain whole-number count per line. This input contract is for individual counts.

FAQ

Yes. Paste up to 10,000 count rows, with one distinct species per line.

Pielou J divides by ln(S), which is zero when S is one. The tool reports it as undefined instead of inventing a value.

No. Richness counts only rows with a positive count.

No. These are summaries of the entered sample, not estimates of unseen species or a correction for survey effort.

About Species Richness and Shannon Diversity Calculator

Paste a single sample’s species counts, one per line. The calculator separates observed richness from abundance-weighted diversity and reports their limits without assigning a habitat-quality score.