The objective of this work is to demonstrate the possibility of performing fast neutron dosimetry up to 5 Sv using optical absorbance of polyallyl diglycol carbonate (PADC) detectors, obtained through grey level analysis of PADC images acquired with a commercial track-counting dosimetry system, and estimate the uncertainties involved. PADCs were irradiated with doses from 100 mSv to 5 Sv (²⁵²Cf source) and etched. PADC images were acquired using the TASLIMAGE™ Neutron Dosimetry System (Track Analysis Systems Ltd.) and analysed to obtain the grey levels and the optical absorbance. The absorbance from different detectors and batches was analysed to determine the uncertainties involved, from which the final uncertainty in the method, ~30% and dominated by the uncertainty in the calibration curve, was estimated. A dose estimation <2 Sv can also be performed using a ‘universal curve’ by normalising the absorbance to that of a detector irradiated with 1 Sv. The data presented here allows the extension of the dose range of track counting systems using no additional equipment, only the images already acquired by the systems.