The research aims to study the effect of some physical properties of the soil as soil components of sand, silt, and clay, as well as bulk density, and the initial soil moisture, on both cumulative infiltration depth, infiltration rate, and basic infiltration rate. Depending on data of 31 laboratory infiltration tests represented by 516 values for cumulative infiltration depth and cumulative infiltration time, including a wide range of change in soil physical properties. Using the statistical program (SPSS), and by applying the nonlinear regression method, the best empirical equation has been derived to estimate the cumulative infiltration depth, with a determination coefficient of 0.975, as a function of some physical properties of soil and in the form of Kostakov's equation to include estimation of basic infiltration rate.