We have developed a simple and accurate method for calculating the equivalent circulating density for drilling fluid which can be used for deepwater drilling calculations. The calculation takes into account depth, the properties of the rock cuttings (size, density), the concentration of solid particles, the geothermal gradient, the water temperature, and the properties of the drilling fluid. We discuss the influence of these factors on the equivalent density. The proposed method will make it possible to reduce risks in deepwater drilling.