Shannon Diversity Index Calculator

The Shannon Diversity Index (H') is a metric used in ecology to quantify the diversity of species in a community. It accounts for both the number of species present (richness) and how evenly individuals are distributed among those species (evenness). Higher H' values indicate greater diversity.

The formula is H' = −Σ(pᵢ × ln(pᵢ)), where pᵢ is the proportion of individuals belonging to species i (i.e., nᵢ / N). You sum this term for every species present in your sample. The result is always a non-negative number.

A higher H' value means greater biodiversity. If H' = 0, only one species is present. The maximum possible H' value (H' max = ln(S)) is reached when all species are equally abundant. In ecological studies, values between 1.5 and 3.5 are typical for most communities.

Shannon Equitability (E) is calculated as E = H' / H'max, where H'max = ln(S). It ranges from 0 to 1, where 1 means all species are equally represented and 0 means complete dominance by a single species. It separates the richness component from the evenness component of diversity.

Species richness (S) is simply the number of different species present — it treats each species equally regardless of abundance. The Shannon Index also considers how individuals are distributed among species, so a community with 5 equally abundant species scores higher than one with 5 species where one dominates all others.

It depends on convention. The natural logarithm (ln, base e) is most common in ecology and is what this calculator uses. Some information-theoretic applications use log base 2 (bits). The choice of log base affects the absolute value of H' but not the relative comparisons between communities.

Yes — as long as your values are proportional to abundance, the calculator will correctly determine each species' proportion relative to the total. Enter raw counts for each species, and the calculator automatically computes pᵢ = nᵢ / N for you.

Species with a count of zero are automatically excluded from the calculation. The mathematical term 0 × ln(0) is defined as 0 by convention (since the limit as p → 0 of p × ln(p) equals 0), so they do not contribute to H'. Leave any unused species fields blank or set to 0.