# Calculation

The core of the methodology is this. We have a fungible, traceable, and culturally translatable metric for conserved biodiversity which is interoperable with other biodiversity metrics and methodologies.

A VBC under the ISBM represents 30 days of 1 hectare of a protected ecosystem with a value corresponding to the baseline [ecosystem value](https://isbm.savimbo.com/baseline-assessment/baseline-ecosystem-categorization) (normalized to [four levels](https://isbm.savimbo.com/calculation/value-calculations)). The protection of the ecosystem is determined by the presence of a qualified [indicator species](https://isbm.savimbo.com/baseline-assessment/indicator-species-selection) and its [integrity score](https://isbm.savimbo.com/calculation/integrity-calculations). Which if <1.0, may result in fractional crediting.&#x20;

Here is an example site, with one year of data showing an interactive view of this methodology. Following, we will explain the sequential steps required to arrive at this view.&#x20;

#### Figure 7. Biodiversity credits appearing and disappearing over time with different species observations.

<figure><img src="https://2009818984-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F0OSjAYvyC9lI8YyZQCxA%2Fuploads%2FOYTuQgTqYy2siNjC6F7C%2FBiodiversity_credit_calculations.gif?alt=media&#x26;token=4f58b887-6000-4093-bea5-cf9e77021636" alt=""><figcaption></figcaption></figure>

It should be noted that calculations are simple in theory, and relatively complex in execution. The complexity has been offloaded to [open-source computer code](https://isbm.savimbo.com/appendices/appendix-g-sample-open-source-code-and-calculation) in order to make the observation points required at a project level simpler.&#x20;

Here we explain the theory and the logic of the computer code but recommend BCPs use automated calculations from a vetted source.&#x20;

However, all calculations can be easily automated, and open-source code for this is available [Appendix G](https://isbm.savimbo.com/appendices/appendix-g-sample-open-source-code-and-calculation) while manual calculations are demonstrated in [Appendix M](https://isbm.savimbo.com/appendices/appendix-m-how-to-calculate-a-biodiversity-credit-by-hand). &#x20;

The calculations are devised to avoid double-crediting under a simplified methodology that does not identify individual species. Any specific hectare of land can only be counted only once at any given time, and cannot achieve a value greater than 1.0, nor will it achieve full crediting if the indicator species found there does not merit it.&#x20;