In order to obtain accurate results from computer simulations of the dynamic behaviour of conveyor belts a detailed description of the resistance forces which are exerted on the moving belt is necessary. In this article an approximate formulation for the total rolling resistance of the belt will be given. This resistance can be divided into three parts: the indentation rolling resistance, the rotation inertia of the rolls of the idler station and the resistance of the bearings of the idler rolls to rotation. An example will be given which shows the order of magnitude of these three parts.