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The biodiversity metric is a habitat based approach used to assess an areas value to wildlife. The metric uses habitat features to calculate a biodiversity value.

The biodiversity metric can be used by:

• ecologists or developers carrying out a biodiversity assessment
• developers who have commissioned a biodiversity assessment
• planning authorities who are interpreting metric outputs in a planning application
• communities who want to understand the impacts of a local development
• landowners or land managers who want to provide biodiversity units from their sites to others

What the metric is for

You can use the biodiversity metric to calculate how a development, or a change in land management, will change the biodiversity value of a site. For example, building houses, planting a woodland or sowing a wildflower meadow.

You can use the metric to:

• assess the biodiversity unit value of an area of land
• demonstrate biodiversity net gains or losses in a consistent way
• measure and account for direct impacts on biodiversity
• compare proposals for a site - such as creating or enhancing habitat on-site or off-site

It can help you design, plan and make land management decisions that take better account of biodiversity. You should use the metric and calculator tool with ecological advice.

The metric calculates the values as biodiversity units. Biodiversity units are calculated using the size of the habitat, its quality and location.

Types of habitat

You can use the biodiversity metric for land and intertidal habitats, including hedgerows, rivers and streams.

The metric assesses existing habitats and planned new habitats created by a development or land change.

Information you need for the calculation tool

To use the metric calculation tool you need to know:

• the types of habitat - on-site and off-site
• the size of each habitat parcel in hectares - or kilometres if it is linear (rivers and streams, hedgerows and lines of trees)
• the condition of each habitat parcel
• whether the sites are in locations identified as local nature priorities

Use the metric

The calculation tools and user guides for the biodiversity metric and small sites metric are published on Natural Englands Access to Evidence website. The user guide describes how to gather the information needed for the metric calculations.

You should expect biodiversity metric 4.0 to be the version you must use from November 2023. The use of the small sites metric is expected to become mandatory from April 2024.

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