The Biodiversity Metric
Understanding what it means for your development
The Statutory Biodiversity Metric assesses biodiversity value using a range of ecological and spatial factors. While the methodology may evolve over time, its core purpose remains the same: to deliver measurable, lasting gains for nature.
What the assessment considers
Every site is different. The Statutory Biodiversity Metric considers several factors when calculating biodiversity value.
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Some habitats naturally support more biodiversity than others. Broadleaved woodland, species rich grassland and wetlands all carry different ecological value.
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Healthy habitats are worth more than degraded habitats. Protecting and restoring existing habitats can therefore play an important role in Biodiversity Net Gain.
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The size of a habitat influences the biodiversity value it can support. Larger, connected habitats generally provide greater ecological benefits.
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Habitats that support local priorities, including Local Nature Recovery Strategies, may carry greater value within the Statutory Biodiversity Metric. This encourages biodiversity to be created where it will have the greatest impact.
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Where habitats are created or enhanced, and their relationship to existing ecological networks.
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Habitats take time to establish. Some can be created relatively quickly. Others take decades to reach their target condition. The Statutory Biodiversity Metric reflects this through the Temporal Risk Multiplier.
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The level of risk and complexity involved in delivering the habitat successfully. The greater the risk of failure, the more habitat has to be created to achieve the same value.
How much biodiversity needs to be created for my development?
Understanding the Statutory Biodiversity Metric early helps you make better planning decisions, identify the right opportunities and avoid unnecessary costs later in the process.
At Biofarm, we help developers understand what the biodiversity metric means for your project, then create and manage the habitats that deliver it.
What is the Statutory Biodiversity Metric?
The biodiversity metric is the standard approach used in England to measure biodiversity before and after development.
It compares the biodiversity value of existing habitats with the value that will remain or be created once a development is complete.
The difference determines whether Biodiversity Net Gain has been achieved and how many biodiversity units are required.
It is more than a calculation. It helps ensure the places we build today continue to support nature for generations to come.
Biofarm insight
The Statutory Biodiversity Metric is about more than numbers. It helps guide where habitats should be created, how they should be managed and how development can leave nature in a better state than before.
Understanding what sits behind the calculation can help you make better decisions earlier, from where BNG is delivered to the balance between on-site and off-site.
Our CPD sessions bring that into the context of your projects. Tailored to your team, we explore the practical implications of BNG, share insight from across the market and discuss live schemes and the questions that matter to you.
Why location matters
One of the most misunderstood parts of the biodiversity metric is location.
Connectivity for wildlife is important. This is why biodiversity is more valuable when it is delivered close to the development it supports. The Biodiversity Metric recognises this through the Spatial Risk Multiplier.
Where biodiversity is created further away, additional biodiversity units may be required.
That is why Biofarm is building a growing network of habitat banks across England. Creating habitats closer to developments helps support planning, reduce unnecessary costs and strengthen local nature recovery.
What is the Spatial Risk Multiplier?
The Spatial Risk Multiplier is the part of the Statutory Biodiversity Metric that accounts for distance. It encourages biodiversity to be delivered as close as possible to the development it supports, and increases the number of units required the further away it is delivered.
Choosing a locally appropriate Biofarm Habitat Bank can help reduce additional biodiversity unit requirements while creating better outcomes for nature.
Planning confidence starts with the right habitat, in the right place.
How Biofarm helps
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Understand your BNG requirements
We’ll review your biodiversity metric and help you understand what the results mean for your project, including the viability of off-site BNG.
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Long term stewardship
We create, manage and monitor every habitat for at least 30 years. We’ll create and care for the habitats over the long term, checking how they develop and reporting on progress. You’ll work directly with us throughout, with a team you can turn to as your project moves forward.
Frequently asked questions
Can’t find what you’re looking for?
Want to go deeper? We run CPD sessions on Biodiversity Net Gain and the metric for developers, planners and consultants.
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The biodiversity metric is normally completed by a suitably qualified ecologist. Biofarm works alongside ecologists, planning consultants and developers to help interpret the results and identify appropriate off site habitat options where required.
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Strategic significance recognises habitats that support local ecological priorities, including Local Nature Recovery Strategies. Creating habitats in these locations can contribute more effectively to wider nature recovery.
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The Spatial Risk Multiplier reflects the importance of creating biodiversity close to the development it supports. Choosing locally appropriate habitat banks can help reduce additional biodiversity unit requirements.
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The Temporal Risk Multiplier recognises that habitats take time to establish. Habitats that take longer to reach their target condition carry greater delivery risk, which is reflected within the Biodiversity Metric.
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Most developments subject to Biodiversity Net Gain will need to use the Statutory Biodiversity Metric to assess biodiversity before and after development and demonstrate how the required net gain will be achieved.
Eligible small developments can use the Small Sites Metric, a simplified version of the statutory metric designed for qualifying smaller schemes.
Your ecologist will usually calculate your site’s baseline and post-development biodiversity values. Biofarm can then help you understand what the results mean for your project, assess the viability of off-site BNG and secure the biodiversity units you need.
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Not every development needs to deliver Biodiversity Net Gain. Exemptions include:
Householder applications, such as home extensions.
Sites of 0.2 hectares or less, where applications were submitted from 6 August 2026.
Wholly temporary developments permitted for five years or less, under rules introduced on 6 August 2026.
Developments affecting less than 25 square metres of habitat and less than five metres of linear habitat, such as hedgerows.
Small sites, temporary developments and developments with very limited habitat impacts still need to meet BNG requirements if they harm a priority habitat. These are habitats recognised as particularly important for nature, such as lowland meadow.
Other exemptions may apply depending on your proposal and when you submitted your planning application.
Unsure what applies to your project? We’ll help you understand the requirements and your next steps.
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Where sufficient Biodiversity Net Gain cannot be delivered on-site, developers may need to secure off-site biodiversity units from professionally managed habitat banks.
Let’s make the Statutory Biodiversity Metric work for your project
Understanding the biodiversity metric is only the first step.
We’ll help you interpret the results, identify the right opportunities and create habitats that support both your development and nature.
Better decisions create better places.
Your success is ours too
Our transparent model is built for mutual commercial benefit.
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investment
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Leave your own legacy
Shape the landscape in a way that truly matters.
Pushing for progress
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