The Dr.Hydraulics allows the user to quickly get nozzle results such as Bit TFA, pressure drop, HSI, Impact Force, etc. based on inputs of bit size, flow rate, nozzles and mud weight. Mathematics is based on a more modern approach and will be applied in leading companies. (Drilling Associates AADE 01-NC-HO-30; AADE-10-DF-HO-26). Equivalent Circulating Density (ECD) is the effective density that combines current mud density and annular pressure drop. ECD is vital for drilling engineering since it limits how depth of each section to be drilled and leads to losses.