IUCN Red List Criteria Calculator

The IUCN Red List is the global standard for assessing a species' extinction risk — this calculator applies those official criteria to classify any species from Least Concern to Critically Endangered. Enter your species' population decline, generation length, extent of occurrence, area of occupancy, number of locations, mature individuals, and whether there are continuing declines or extreme fluctuations. You'll get an IUCN Threat Category, the specific criteria met, a risk score out of 10, and an assessment confidence percentage.

%

Percentage decline in population over the past 10 years or 3 generations

years

Average age of reproductive maturity

km²

Area of the smallest polygon containing all known sites

km²

Area actually occupied by the species

Geographically distinct areas with different threats

Total number of reproductively capable individuals

Is there evidence of ongoing population decline?

Does the species experience extreme population fluctuations?

Results

IUCN Threat Category

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Criteria Met

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Risk Score

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Assessment Confidence

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Results Table

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Frequently Asked Questions

What assessments are accepted for the IUCN Red List?

IUCN accepts assessments from SSC members, Red List Authorities, Red List Partners, and specialists with sufficient species knowledge. All assessments must follow IUCN Red List Categories and Criteria methodology.

How is generation length calculated for species assessment?

Generation length represents the average age of reproductive maturity in a population. It's used to scale time-based measurements in red listing and varies significantly between species types.

What's the difference between Extent of Occurrence and Area of Occupancy?

Extent of Occurrence is the area of the smallest polygon containing all known sites, while Area of Occupancy is the area actually occupied by the species within its range.

How many locations are needed to avoid Critically Endangered status?

Under criterion B, species with fewer than 5 locations may qualify for Critically Endangered status if other conditions are met, such as continuing decline or extreme fluctuations.

What population decline percentage triggers Endangered status?

A population decline of ≥50% over 10 years or 3 generations (whichever is longer) may qualify a species for Endangered status under criterion A.

How reliable are IUCN Red List assessments?

IUCN Red List assessments undergo rigorous review processes and are based on standardized criteria. Assessment confidence depends on data quality and availability for each species.

Can species move between threat categories over time?

Yes, species can be reassessed and moved between categories as new data becomes available or their conservation status changes due to threats or conservation actions.

What happens after a species is assessed using these criteria?

Completed assessments are submitted to the IUCN Red List Unit for review and potential publication on The IUCN Red List of Threatened Species database.