Squat is a steady downward displacement consisting of a translation and rotation due to the flow of water past the moving hull. Nowadays, with the considerable increases in the size and speed of ships, the importance of accurate determination of the squat parameter in the design of waterways has increased. Squat has an important role both in economic costs of design and construction of new waterways and safe movement of ships in existing waterways. Various methods can be used for squat estimation including empirical relations, laboratory test models and numerical modeling. In this paper, based on PIANC recommendations, different empirical formulas are used to estimate the squat of the incoming ships to some of the main ports of Iran on the horizon of 1404. Finally, by concluding the results, suggestions are given for calculating the squat of different vessel types in the design of Iranian ports waterways.