Shannon Diversity Index
Calculate Shannon diversity index (Shannon-Wiener index) for ecological biodiversity. Get H index, evenness, richness, and species composition charts with breakdown.
Enter the number of individuals for each species, separated by commas. E.g. "5,12,2,5,1" for 5 species.
About This Calculator
The Shannon Diversity Index Calculator (also known as the Shannon-Wiener index) helps ecologists, biologists, and environmental scientists quantify species diversity within a community. Unlike simple species counts, the Shannon index accounts for both species richness (the number of different species) and species evenness (how evenly individuals are distributed among species). This makes it one of the most widely used biodiversity metrics in ecology research and environmental monitoring.
The calculator uses the standard Shannon diversity formula H = −Σ(pᵢ × ln(pᵢ)), where pᵢ represents the proportion of individuals belonging to species i. You can choose between natural logarithm (ln), base 2, or base 10. The tool also calculates evenness (E = H / Hmax) which ranges from 0 to 1, and displays a detailed breakdown showing each species' proportion and contribution to the overall index. Results are visualized with both bar charts (species proportions) and pie charts (entropy contribution).
The Shannon diversity index is applied worldwide in ecology research, conservation biology, and environmental impact assessment. In the US, the EPA uses species diversity indices for water quality biomonitoring. In the UK, Natural England and the Joint Nature Conservation Committee (JNCC) employ diversity indices for habitat assessment. In India, the National Biodiversity Authority and forest departments use Shannon index for biodiversity monitoring in wildlife sanctuaries and national parks. The index is also used in agriculture to measure crop diversity, in urban ecology to assess green space biodiversity, and in corporate biodiversity reporting under frameworks like TNFD (Taskforce on Nature-related Financial Disclosures).
Frequently Asked Questions
What is the Shannon diversity index?
The Shannon diversity index (also called the Shannon-Wiener index) is a popular ecological metric that quantifies species diversity in a community. It accounts for both species richness (number of species) and evenness (relative abundance). The index value typically ranges from 1.5 to 3.5 in real-world ecological data, with higher values indicating greater diversity.
How is the Shannon diversity index calculated?
The Shannon diversity index is calculated using the formula H = -Σ(pᵢ × ln(pᵢ)), where pᵢ is the proportion of individuals belonging to the i-th species. First, calculate the proportion of each species by dividing each species count by the total number of individuals. Then multiply each proportion by its natural logarithm, sum all values, and multiply by -1.
What is a good Shannon diversity index value?
In ecology, Shannon diversity index values typically range from 1.5 to 3.5. Values below 1.5 indicate low diversity, 1.5 to 2.5 indicate moderate diversity, and above 2.5 indicate high diversity. The theoretical maximum depends on the number of species and equals ln(k) where k is the number of species. An evenness value close to 1 indicates all species are equally abundant.
What is the difference between Shannon index and Simpson index?
The Shannon index (H) is more sensitive to species richness and gives more weight to rare species, while the Simpson index (D) is more sensitive to dominance of common species. The Shannon index typically ranges from 0 to ln(k), while Simpson ranges from 0 to 1. Ecologists often use both indices together for a more complete picture of biodiversity.
Can the Shannon diversity index be over 1?
Yes, the Shannon diversity index can easily exceed 1. For example, a community with 6 equally abundant species yields an index of approximately 1.79. The theoretical maximum increases with species richness: for 100 species it is 4.605, for 1,000 species it is 6.908, and for all eukaryotic species on Earth it would be approximately 15.98.
What logarithm base should I use for the Shannon index?
Natural logarithm (ln) is the most commonly used base for the Shannon diversity index in ecology. Base 2 and base 10 are also used but produce different absolute values. The choice of base does not affect the ranking or interpretation of diversity — it only scales the index. Evenness is calculated the same way regardless of base since both H and Hmax use the same base.
What does evenness tell us in the Shannon index?
Evenness (E = H / ln(k)) measures how evenly individuals are distributed among species. It ranges from 0 to 1, where 1 means all species have equal abundance. A community with high species richness but very low evenness may still have a moderate Shannon index, while a community with moderate richness but high evenness can achieve high diversity scores.
How do I interpret a Shannon index of 0?
A Shannon diversity index of 0 indicates that there is no diversity — only one species is present in the community. In this case, the proportion of the single species is 1.0 and ln(1.0) = 0, resulting in H = 0. This is the absolute minimum value of the index and indicates a monoculture or a completely homogeneous habitat.