Uncertainties in the ISO (1996) and Swedish (SEPA, 2012) calculation methods are expected to have a SD of approximately 4dB for distances less than 1km. This is based on the 3dB SD given in the ISO (1996) method, the SD for the wind turbine sound power level of 2dB (Keith et al., 2016) and the comparatively small additional uncertainty from GPS position data (SD1dB).