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Shannon Diversity Index Calculator

Calculate the Shannon-Wiener diversity index (H') from species abundance data. Enter individual counts for up to five species to measure biodiversity in ecological surveys.

Reviewed by Christopher FloiedPublished Updated

This free online shannon diversity index calculator provides instant results with no signup required. All calculations run directly in your browser — your data is never sent to a server. Enter your values below and see results update in real time as you type. Perfect for everyday calculations, homework, or professional use.

Minimum: 0

Number of individuals of species 1

Minimum: 0

Number of individuals of species 2

Minimum: 0

Number of individuals of species 3 (enter 0 to exclude)

Minimum: 0

Number of individuals of species 4 (enter 0 to exclude)

Minimum: 0

Number of individuals of species 5 (enter 0 to exclude)

Results

Shannon Index (H')

1.2799

Species Richness

4

Evenness (J')

0.9232

How to Use This Calculator

1

Enter your input values

Fill in all required input fields for the Shannon Diversity Index Calculator. Most fields include unit selectors so you can work in your preferred unit system — metric or imperial, whichever matches your problem.

2

Review your inputs

Double-check that all values are correct and that you have selected the right units for each field. Incorrect units are the most common source of calculation errors and can produce results that are off by factors of 2, 10, or more.

3

Read the results

The Shannon Diversity Index Calculator instantly computes the output and displays results with units clearly labeled. All calculations happen in your browser — no loading time and no data sent to a server.

4

Explore parameter sensitivity

Try adjusting individual input values to see how the output changes. This is a quick and effective way to develop intuition about how different parameters influence the result and to identify which inputs have the largest effect.

When to Use This Calculator

  • •Use the Shannon Diversity Index Calculator when you need accurate results quickly without the risk of manual computation errors or unit conversion mistakes.
  • •Use it to verify calculations made by hand or in spreadsheets — an independent check can catch errors before they lead to costly decisions.
  • •Use it to explore how changing input parameters affects the output — a quick way to develop intuition and identify the most influential variables.
  • •Use it when collaborating with others to ensure everyone is working from the same numbers and applying the same assumptions.

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About Shannon Diversity Index Calculator

The Shannon Diversity Index Calculator computes the Shannon-Wiener diversity index (H'), a widely used measure of biodiversity in ecological research. The index accounts for both species richness (the number of different species present) and evenness (how equally individuals are distributed among those species). A community with many species distributed evenly has a high H' value, while one dominated by a single species has a low H'. The calculator also outputs the evenness index (J'), which normalises H' to a 0-1 scale. These metrics are standard in ecological field surveys, environmental impact assessments, and conservation planning. Enter the individual counts for up to five species to obtain instant biodiversity metrics.

The Math Behind It

The Shannon diversity index was adapted from information theory by ecologist Robert MacArthur and mathematician Claude Shannon. In information theory, entropy measures the uncertainty in predicting the next symbol in a message. Analogously, H' measures the uncertainty in predicting the species of a randomly chosen individual from a community. Higher uncertainty means higher diversity. The formula is H' = -SUM(pi * ln(pi)), where pi is the proportion of individuals belonging to species i and ln is the natural logarithm. The summation runs over all species with non-zero abundance. Species with zero individuals are excluded because their proportion is zero and the limit of p*ln(p) as p approaches 0 is 0. H' is bounded between 0 (a community with only one species) and ln(S) (a community where all S species are equally abundant). The ratio H'/ln(S) gives the evenness index J', which ranges from 0 (maximally uneven) to 1 (perfectly even). Typical H' values in nature range from 1.5 to 3.5, with most terrestrial ecosystems falling between 1.5 and 2.5. Tropical rainforests and coral reefs can reach values above 4.0. Values below 1.0 suggest a highly disturbed or dominated community. The Shannon index is sensitive to rare species, which is both a strength and a limitation. Including rare species increases H' but rare species may be missed in small sample sizes. Simpson's diversity index (1 - D), which emphasises dominant species, is sometimes preferred for small samples. Both indices are commonly reported together in ecological studies. When comparing diversity between sites, ensure samples are of comparable size, as H' tends to increase with sample size due to the accumulation of rare species.

Formula Reference

Shannon Diversity Index

H' = -Σ(pi * ln(pi))

Variables: pi = proportion of individuals belonging to species i, ln = natural logarithm

Shannon Evenness

J' = H' / Hmax = H' / ln(S)

Variables: H' = Shannon index, S = total number of species

Worked Examples

Example 1: Four-Species Meadow Survey

A meadow survey finds 40 individuals of species A, 30 of species B, 20 of species C, and 10 of species D.

Step 1:Total N = 40 + 30 + 20 + 10 = 100
Step 2:Proportions: pA = 0.40, pB = 0.30, pC = 0.20, pD = 0.10
Step 3:H' = -(0.40*ln(0.40) + 0.30*ln(0.30) + 0.20*ln(0.20) + 0.10*ln(0.10))
Step 4:H' = -(0.40*(-0.9163) + 0.30*(-1.2040) + 0.20*(-1.6094) + 0.10*(-2.3026))
Step 5:H' = -((-0.3665) + (-0.3612) + (-0.3219) + (-0.2303)) = 1.2799
Step 6:Evenness J' = 1.2799 / ln(4) = 1.2799 / 1.3863 = 0.9233

The Shannon index is H' = 1.2799 with evenness J' = 0.9233, indicating moderately high diversity and good evenness.

Example 2: Highly Dominated Community

A disturbed site has 90 individuals of species A and 10 of species B.

Step 1:Total N = 90 + 10 = 100
Step 2:Proportions: pA = 0.90, pB = 0.10
Step 3:H' = -(0.90*ln(0.90) + 0.10*ln(0.10))
Step 4:H' = -(0.90*(-0.1054) + 0.10*(-2.3026)) = 0.3251
Step 5:Evenness J' = 0.3251 / ln(2) = 0.3251 / 0.6931 = 0.4690

H' = 0.3251 with J' = 0.4690, indicating low diversity due to strong dominance by one species.

Common Mistakes & Tips

  • !Using log base 10 instead of natural logarithm (ln). The Shannon index conventionally uses ln; using log10 gives a different numerical value and makes comparisons with published literature incorrect.
  • !Including species with zero counts in the summation, which produces undefined results (ln(0) is undefined). Zero-count species should be excluded.
  • !Comparing H' values between sites with very different sample sizes without accounting for the sample-size effect on species detection.

Related Concepts

Carrying Capacity

The maximum population an ecosystem can sustain, which influences species composition and diversity.

Simpson's Diversity Index

An alternative diversity measure (1 - D) that gives more weight to dominant species and is less sensitive to rare species than the Shannon index.

Used in These Calculators

Calculators that build on or apply the concepts from this page:

Carrying Capacity Calculator

Frequently Asked Questions

What is a 'good' Shannon diversity index value?

Most natural ecosystems have H' values between 1.5 and 3.5. Values above 3.0 indicate high diversity. Values below 1.0 suggest a disturbed or heavily dominated community. There is no universal 'good' value; it depends on the ecosystem type.

What is the difference between Shannon and Simpson diversity?

The Shannon index is more sensitive to rare species, while Simpson's index gives more weight to common species. Shannon measures uncertainty, while Simpson measures the probability that two randomly chosen individuals belong to the same species.

Can I use this for more than five species?

This calculator supports up to five species for simplicity. For larger datasets, use the same formula H' = -SUM(pi*ln(pi)) in a spreadsheet or statistical software like R.

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