Shannon Diversity Index Calculator

The Shannon diversity index (H') is a mathematical measure that quantifies the diversity of species in a community. It takes into account both the number of species (richness) and how evenly individuals are distributed among those species (evenness). See also our Population Growth Calculator (Exponential).

The Shannon index tells you how diverse a community is. Higher values indicate greater diversity, meaning more species are present and/or individuals are more evenly distributed among species. Lower values suggest less diversity with fewer species or dominance by one species.

Values typically range from 0 to 5. A value of 0 indicates no diversity (only one species present). Values of 1-2 suggest low to moderate diversity, while values above 3 indicate high diversity. The theoretical maximum depends on the number of species present.

Yes, the Shannon index can definitely exceed 1. In fact, most diverse ecological communities have values between 1.5 and 4.5. The maximum possible value increases logarithmically with the number of species present in the community. You might also find our Doubling Time Calculator (Population) useful.

Natural logarithm (ln) is most commonly used in ecology and gives results in units called 'nats'. Base 2 gives results in 'bits' and base 10 in 'decits'. The choice doesn't affect comparisons between communities as long as you're consistent.

Evenness (J') measures how equally individuals are distributed among species. It ranges from 0 to 1, where 1 indicates perfect evenness (equal numbers of each species) and values closer to 0 indicate dominance by one or few species.

This calculator supports up to 8 species entries. For larger datasets with more species, you can calculate the Shannon index using statistical software or spreadsheet applications with the same formula: H' = -Σ(pi × ln(pi)). Check out our Effective Population Size (Ne) Calculator as well.