Species Richness Calculator

Work out species richness instantly with clear inputs, formula shown and shareable results.

About Species Richness Calculator

Applies the Chao1 estimator, which infers undetected species from the number seen only once or twice in the sample.

Formula

Chao1 estimator

Chao1 = S_obs + f1^2 / (2 f2), where f1 is singletons and f2 doubletons; the bias-corrected form is used when f2 is zero

Worked example

With the default values below, Species Richness Calculator returns Chao1 richness estimate of 30.00. Change any input above and every figure here is recalculated in your browser.

Inputs used

Species observedaccepts 1–10,000: 24
Species seen onceaccepts 0–10,000: 6
Species seen twiceaccepts 0–10,000: 3

Results

Chao1 richness estimate: 30.00
Species observed: 24
Estimated undetected species: 6.00
Inventory completeness: 80.00%

Step by step

1Values used
2Chao1 estimator
3Chao1 richness estimate= 30.00
4Species observed= 24
5Estimated undetected species= 6.00
6Inventory completeness= 80.00

Assumptions and limits

The result is derived only from the 3 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

Why do singletons predict hidden species?

Many species seen once implies the sample is far from saturated, so more species remain undetected.

Is Chao1 an upper bound?

It is a lower bound on true richness, and it rises as sampling continues until the asymptote is approached.