Passive ranging is the process of estimating the distance between an observer (own-ship) and one or more objects (targets) by using passive sensors and angle measurements only, without electromagnetic or acoustic emissions. It is the baseline technique to complete the three dimensional tracking capability of IRST systems, able to automatically search, detect and track targets with generally higher angular resolution than Radars in completely silent mode. As well-known from literature, range is univocally linked to angle only data, when specific relative dynamics occur. In other cases, when such univocal relation does not hold, range estimation is still considered an open research topic. In this paper we select a set of informative cases, derived from our experience in analyzing real sorties data and compare four popular algorithms on the basis of a set of new metrics that, in our opinion, captures the system performance in terms of usability and reliability. Ranging algorithms performance is usually evaluated by means of distance-based metrics (as RMSE) which focus on accuracy of the estimation. Usability and reliability are taken into account here by introducing what we call the Average Range Declaration Length (ARDL) and the Truth-Representative Score (TRS).