The influences of liquid fuel temperature, pressure and injection rate on fuel contraction coefficient and Reynolds number during a fuel injection were investigated in this paper. Nozzle geometry parameters remained constant during the whole numerical analysis. Calculations were performed with a standard diesel fuel D2. Increase in liquid fuel temperature cause increase in fuel contraction coefficient. Fuel temperature increase resulted in a slight increase in contraction coefficient at low fuel pressures, while at high fuel pressures increase in fuel temperature causes significant increase in fuel contraction coefficient. Increase of fuel pressure resulted in a decrease in liquid fuel contraction coefficient, for every fuel injection rate and for every fuel temperature. Reynolds number increases with an increase in fuel temperature and also with an increase in fuel injection rate. The main goal of presented analysis is to be usable not only for one fuel injector and its nozzles, but for a large number of the fuel injectors and for many liquid fuels.