How to Calculate the Shannon-Weaver Diversity Index

Written by carter mcbride
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How to Calculate the Shannon-Weaver Diversity Index
The Shannon-Weaver index looks at biodiversity in an ecosystem. (frog on a hand - black-eyed tree frog sitting on a hand image by Christophe Fouquin from

The Shannon-Weaver diversity index looks at how a species is distributed in the an ecosystem. To perform this calculation, you need to sample a population by taking a look at a given area, counting the different species in the population and assessing their abundance there. The Shannon-Weaver diversity index is also known as the Shannon index or Shannon-Wiener index. This is an important measurement for biodiversity.

Skill level:


  1. 1

    Find the number of a specific species in an population. For example, you might look at a pond and find 20 individual frogs of the same species out of 1,000 total animals found.

  2. 2

    Divide the number of a species you are looking at by the number in the population to calculate the relative abundance. In the example, 20 frogs divided by 1,000 animals equals 0.02.

  3. 3

    Calculate the natural log of the abundance. Log calculations are easiest on a calculation using the Ln button on the calculator. The Ln of 0.02 equals -3.912023005.

  4. 4

    Multiply the abundance by the natural log of the abundance. This is the sum of the abundance and natural log of the abundance. In the example, -3.912023005 times 0.02 equals -0.07824046.

  5. 5

    Repeat these steps for each species you found in the sampling. For example, if you found 30 individual frogs of a different species, then you would repeat steps 1 through 4 using 30 individual frogs of the different species.

  6. 6

    Add together the sum of the abundance and natural log of the abundance for each species. This is the number you calculated in Step 4. As part of the example, assume the sum of these numbers from the example is -1.34324.

  7. 7

    Multiply the amount calculated in Step 6 by -1. This is H'. In the example, -1.34324 times -1 equals 1.34324.

  8. 8

    Raise e to the power of H'. You calculated H' in Step 7. E is a constant at 2.71828183. In the example, 2.71828183 raised to the power of 1.34324 equals 3.831437276. This is the Shannon-Weaver diversity index for this example.

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