RSustain UK

Biodiversity Net Gain Calculator — Defra Metric 4.0

Calculate habitat units, assess net gain against the mandatory 10% target under the Environment Act 2021, and get habitat creation recommendations.

Environment Act 2021 Defra Metric 4.0 NPPF 2023
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Important: This tool currently reflects UK methodology (Environment Act 2021, Defra Metric 4.0). An India-specific version aligned with NBA biodiversity framework and Biological Diversity Act is in development. Results should not be used for Indian regulatory submissions.
1Baseline
2Post-Dev
3BNG Result
10%
minimum BNG required under Environment Act 2021
Defra Metric 4.0
statutory calculation methodology
30-year
habitat management obligation

Since February 2024, all major English planning applications must demonstrate a minimum 10% Biodiversity Net Gain. This tool provides a simplified Defra Metric 4.0 calculation — comparing baseline habitats against post-development proposals to determine if the 10% threshold is met.

Ecologist Planning Consultant Developer BNG Environment Act

Baseline Habitats

Enter existing habitats on site before development (Defra Metric 4.0 methodology)

Jurisdiction

Environment Act 2021: All planning permissions in England granted after February 2024 must deliver a minimum 10% Biodiversity Net Gain, maintained for at least 30 years.

Baseline Habitat Parcels

Habitat TypeArea (ha)ConditionDistinctiveness
+ Add Baseline Habitat

Post-Development Habitats

Enter proposed habitats after development, including retained, enhanced, and created habitats

Post-Development Habitat Parcels

Habitat TypeArea (ha)Target ConditionDistinctiveness
+ Add Post-Development Habitat