In the Netherlands a large variety exists in the used widths of inland port entrances. In addition, multiple entrance layouts are applied. Currently, guidelines are missing for the design of inland port entrances along flowing waters with flow velocities larger than 0.5 m/s. A more generic insight into the minimum required nautical safe entrance width and most efficient entrance layout can reduce the design costs and time. The objective of this research was to find the minimum required nautical safe entrance width for generic situations for inland ports along flowing waters in non-tidal areas. To find this minimum safe entrance width, the most efficient entrance layout was determined. The influence of different design parameters was studied to provide the most efficient situation. Moreover, an insight into the influence of these parameters was needed to determine the effect on the most efficient situation when changing these parameters. A fast-time simulation study was chosen to analyse the influence of different design parameters on the entrance width. A rectangular entrance layout and a mathematical ship model comparable with a loaded CEMT class Va ship were used. Flow velocities between 1.0 and 2.5 m/s were taken into account. Moreover, the influence of the waterway width, entrance width, length and angle were analysed with the simulation study. The fast-time simulation program SHIPMA was used to perform the simulation study. As a result of the simulation study, it was found that the most efficient entrance angle is 120 degrees. Note that this is an entrance orientation in downstream direction. Also from a viewpoint of minimising siltation, this angle is more favourable than an angle of 90 degrees or smaller. The required entrance widths for arrivals sailing upstream and manoeuvring forward into the port are circa 55 and 80 meters, for flow velocities of respectively 1.0 and 2.5 m/s. For the determined most efficient layout, the forward manoeuvres into the port when sailing downstream were replaced by backward manoeuvres. For these backward manoeuvres the required entrance widths are circa 70 and 90 meters, for flow velocities of respectively 1.0 and 2.0 m/s. A linear relation was observed between the flow velocity and the required entrance width. For the most efficient entrance layout, it was found that the sensitivity of the entrance length, width and angle was small. These results are only valid for an available waterway width larger than 90 meters. For smaller waterway widths additional research is required. Furthermore, it should be mentioned that the limitations of the SHIPMA model also apply for the acquired research results. The most important limitation is that human interference was not included in this research. Besides, only a limited amount of design parameters was included in the simulation study. Additional research is required to study the influence of other design parameters on the required entrance width.