Biodiversity Intactness Index Calculator

Enter your region's land use data — including percentages of primary vegetation, secondary vegetation, cropland, pasture, and urban area — and the Biodiversity Intactness Index Calculator estimates your region's BII score relative to a pristine baseline. You'll also see a breakdown of how each land use type contributes to biodiversity loss, plus compositional similarity and total abundance index scores. Also try the Shannon Diversity Index Calculator.

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Percentage of land that is undisturbed primary forest or natural habitat.

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Regrowth vegetation on previously disturbed land.

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Percentage of land used for cultivated crops.

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Land used for livestock grazing or managed pasture.

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Percentage of land covered by cities, roads, and infrastructure.

Select the dominant biome — affects baseline biodiversity sensitivity weighting.

Overall intensity of human pressure beyond land use (e.g. hunting, pollution, fragmentation).

Results

Biodiversity Intactness Index (BII)

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Total Abundance Index

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Compositional Similarity Index

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Intactness Category

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Estimated Biodiversity Loss

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Results Table

Frequently Asked Questions

What is the Biodiversity Intactness Index (BII)?

The Biodiversity Intactness Index is a metric that measures how intact local ecosystems are compared to their natural, undisturbed baseline. A BII of 100% means biodiversity is fully intact, while lower scores indicate progressive ecological disruption due to land use change, habitat loss, or other pressures. It was originally proposed in 2005 and developed using the PREDICTS database by the Natural History Museum. See also our Island Biogeography Calculator.

What does a BII score below 90% mean?

Scientists consider a BII below 90% to represent a significant ecological threshold, beyond which ecosystems may struggle to maintain their functions and resilience. Many regions globally now fall below this level due to agricultural expansion and urbanisation. The Kunming-Montreal Global Biodiversity Framework (GBF) uses BII as a complementary indicator to monitor progress on biodiversity goals.

What are Total Abundance and Compositional Similarity in the BII formula?

BII is the product of two components: Total Abundance (the average abundance of originally-present species relative to a pristine baseline) and Compositional Similarity (a measure of how similar the current species community is to the original community in composition). Both components are affected by land use type and intensity.

Which land use types cause the most biodiversity loss?

Urban areas and intensive cropland typically cause the greatest biodiversity loss, with very low abundance and compositional similarity factors compared to primary vegetation. Pasture and secondary vegetation represent intermediate disturbance levels, while primary vegetation retains the highest intactness. The biome type also influences sensitivity — tropical forests host more endemic species and are especially vulnerable. You might also find our Logistic Growth Calculator useful.

What is the PREDICTS database?

PREDICTS (Projecting Responses of Ecological Diversity In Changing Terrestrial Systems) is a global database that aggregates biodiversity data from hundreds of studies comparing species abundance and composition at sites under different land uses versus undisturbed reference sites. It forms the empirical backbone of BII calculations produced by the Natural History Museum.

Can the BII calculator account for habitat fragmentation?

This simplified calculator estimates BII based on land use proportions, biome type, and disturbance intensity — key drivers that correlate with fragmentation effects. Full scientific BII calculations also incorporate spatial fragmentation metrics and species-level data from the PREDICTS database, which require GIS raster data and statistical modelling beyond the scope of a web calculator.

What are the limitations of this BII estimate?

This calculator provides an educational estimate based on published land-use abundance and similarity coefficients. It does not incorporate site-level species data, spatial connectivity, invasive species effects, or climate projections. For policy-grade BII assessments, use the Natural History Museum's Biodiversity Trends Explorer or the BON in a Box pipeline with full PREDICTS data.

How can BII be improved in a region?

Restoring degraded land to secondary or primary vegetation, reducing agricultural intensification, protecting remaining primary habitats, and reducing urban sprawl all increase BII. Even partial restoration of cropland or pasture to secondary vegetation can meaningfully raise abundance and compositional similarity scores over time.