A method is developed for assigning a probability to a fingerprint, including a partial print, based on the number of individual (Galton) characteristics present. A multinomial model is used, the categories of which are the individual characteristics and combinations of them. The negative of the logarithm of the probability of any particular configuration is related to the entropy function of information theory. The parameters of the model are estimated from data (fingerprints). Confidence bounds are obtained for the negative log probability of any configuration.