Abstract: A premium for stop loss insurance for a fleet of vehicles is calculated as a stop loss premium for an assumed loss distribution having only losses with a value of one of zero and maximum individual loss. The stop loss premium is calculated based on a loss frequency, a maximum individual loss, and a deductible. The loss frequency is calculated by dividing an expected total loss by the maximum individual loss. Subsets of the fleet of vehicles are associated with different treaty durations. For each treaty duration a stop loss premium is calculated for the fleet of vehicles. Subsequently, for each treaty duration a premium is calculated for the subset of the fleet of vehicles associated with the treaty duration by weighting the stop loss premium, calculated for the fleet of vehicles, with the number of vehicles in the subset.