Defining an appropriately scaled ‘Area of Influence’ is integral to high level screening processes that aim to identify important biodiversity features that may generate risk. To date however, there lacks consensus or quantitative guidance on appropriate buffers to be applied in different contexts. Understanding the factors underlying variation in the distances impacted by sites forms the foundations of a decision-making framework, presented here, to address this knowledge gap. Available literature to create generalised rules is disparate, and there is a lack of research that compares pressures between sectors and habitats systematically. However, by using the best information available, this document suggests approaches that should be applied for direct impacts. Although indirect and induced effects are important to consider, these are not covered here and will be addressed in a subsequent brief.