The **Shannon Diversity Index** (sometimes called the Shannon-Wiener Index) is a way to measure the diversity of species in a community.

Denoted as *H*, this index is calculated as:

*H* = -Σ*p*_{i} * *ln(p*_{i})

where:

**Σ:**A Greek symbol that means “sum”Natural log*ln*:The proportion of the entire community made up of species*p*_{i}:*i*

The higher the value of *H*, the higher the diversity of species in a particular community. The lower the value of *H*, the lower the diversity. A value of *H* = 0 indicates a community that only has one species.

The Shannon Equitability Index is a way to measure the evenness of species in a community. The term “evenness” simply refers to how similar the abundances of different species are in the community.

Denoted as *E _{H}*, this index is calculated as:

*E _{H}* =

*H*/

*ln*(

*S*)

where:

The Shannon Diversity Index*H*:The total number of unique species*S*:

This value ranges from 0 to 1 where 1 indicates complete evenness.

The following step-by-step example shows how to calculate the Shannon Diversity Index and the Shannon Equitability Index for a given community.

**Step 1: Collect the Data**

Suppose a biologist wants to measure the diversity of species in a local forest. She collects the following data:

**Step 2: Calculate the Proportions**

Next, the biologist can calculate the proportion of the community made up of each species.

For example, there are a total of 105 individuals and 40 are classified as species A. Thus, species A makes up 40 /105 = **0.38** of the total community.

She can perform a similar calculation for each species:

**Step 3: Calculate the Natural Log of the Proportions**

Next, she can calculate the natural log of each proportion:

**Step 4: Multiply the Proportions by the Natural Log of the Proportions**

Next, she can multiply the proportions by the natural log of the proportions:

**Step 5: Calculate the Shannon Diversity Index**

Lastly, she can use the following formula to calculate the Shannon Diversity Index:

*H* = -Σ*p*_{i} * *ln(p*_{i})

For this example, she can take the sum of the last column and multiply by negative one:

The Shannon Diversity Index for this community is **1.49**.

She can also use the following formula to calculate the Shannon Equitability Index:

*E _{H}* =

*H*/

*ln*(

*S*)

For this example, there are *S* = 5 total species, so see can calculate this index to be:

*E _{H}* = 1.49 /

*ln*(5) =

**0.92**.

**Additional Resources**

Feel free to use this Shannon Diversity Index Calculator to automatically calculate the Shannon Diversity Index for any dataset.