For the past 10 years, rubber elasticity theory has been applied to coal to calculate the number-averaged molecular weight between branch points (M(c)) and the number-averaged molecular weight of aromatic/hydroaromatic clusters (M(o)). In the equations that have been proposed in the context of coal, the average number of statistical links between branch points (N) was always assumed to be equal to the average number of clusters between branch points (N’). The present paper demonstrates that this assumption is invalid for highly cross-linked polymer networks. Modified equations are proposed for which the assumption N = N’ is no longer considered valid. The main consequence of the modification is that the number-averaged molecular weight of coal clusters is greater than previously reported.