Species Richness Index Calculator

Species Richness Index Calculator: Margalef's Index

Raw species counts are misleading on their own — larger samples almost always turn up more species, regardless of how genuinely diverse a community is. Margalef's Index corrects for this by normalizing species count against sample size, making richness comparable across surveys of different sizes.

The Formula

d = (S − 1) / ln(N)

Worked Example

A survey finds 15 species among 200 individuals sampled.

d = (15 − 1) / ln(200) = 2.6423

How to Use This Calculator

1. Enter the number of species found (S).
2. Enter the total number of individuals sampled (N).
3. Click Calculate to get the species richness index.

Related Calculations

Pair with the Shannon Diversity Index Calculator for a fuller picture of community diversity beyond raw richness.