The report describes the data required, and the methods used, to estimate collision risk. It is accompanied by a worked example and R code (available at http://dx.doi.org/10.7489/1657-1), which enables the collision risk calculations to be performed in a standardised and reproducible way. In the UK, the most frequently used avian collision risk model is commonly known as ‘the Band model’ (Band, Madders & Whitfield 2007) and was originally conceived in 1995. Since then it has undergone several iterations with the most recent associated with the Strategic Ornithological Support Services (SOSS) (Band 2012a; b). The Band model (Band 2012b) provides four different options for calculating collision risk. • Option 1 - Basic model, i.e. assuming that a uniform distribution of flight heights between the lowest and the highest levels of the rotors and using the proportion of birds at risk height as derived from site survey. • Option 2 - Basic model, but using the proportion of birds at risk height as derived from a generic flight height distribution provided. • Option 3 - Extended model and using a generic flight height distribution. • Option 4 - Extended model and using a flight height distribution generated from site survey.