This document specifies a computational method (in line with ISO 17201-4) for estimating the acoustic source data of muzzle blast and explosions on the basis of non-acoustic data for firearms with calibres less than 20 mm and explosions less than 50 g TNT equivalent. This document addresses those cases where no source measurements exist. This document can also be used as an interpolation method between measurements of muzzle blast. Source data are given in terms of spectral angular source energy covering the frequency range from 12,5 Hz to 10 kHz and can be used as data input for sound propagation calculation. This document is not applicable to the prediction of sound levels for the assessment of hearing damage; neither can it be used to predict sound pressure levels nor sound exposure levels at distances where linear acoustics do not apply.