In one aspect, there is disclosed a method of detecting a hydrogen leak in a fuel cell system, including the steps of (a) calculating a mass of hydrogen in a fuel tank, HT new, at a time step, (b) calculating a mass of the hydrogen consumed by the fuel cell at the time step, HFcp new, (c) calculating a total amount of hydrogen that has left the tank from a start to the time step, HTcons, (d) calculating a total amount of hydrogen consumption, HFcpcons, (e) calculating a difference between HTcons and HFcpcons at the time-step, (f) determining if the difference is above a predetermined threshold, and (g) performing an action based on the determination of step (f).