The crack widths in reinforced concrete structures are affected by various influencing parameters, such as the tensile strength of the concrete, which is a highly variable parameter. While safe predictions of crack widths are possible with the existing models supplied in the code provisions accompanied by suitable safety factors, there are large discrepancies between the experimentally measured crack widths and the calculated values. Even within a uniaxial tensile test on reinforced concrete components, several crack parameters (spacings and widths) are usually measured. To further investigate the effects of scattering input parameters on the distribution of crack parameters, a crack propagation model (CPM) is developed, which is a powerful tool that can be used to observe sequential cracking of uniaxially loaded reinforced concrete components. In the present paper, the background of the scattering of the concrete tensile strength will be explained and the procedure for the simulation in the CPM, including the investigation of different bond–slip relationships, will be introduced. Finally, the CPM will be used to calculate experimental crack parameters and the distribution of the calculated crack parameters will be discussed.