Filling losses in tanks due to the expansion of the liquid into the tank and the vapors that are forced out of the tank are generally called displacement losses. Restrictions on vaporization loss of petroleum products give added emphasis to the accurate prediction of vapor pressure and hydrocarbon losses for petroleum products. In this work, firstly, a simple-to-use correlation is developed to estimate the true vapor pressure of liquefied petroleum gas (LPG) and natural gasoline as a function of Reid Vapor pressure (RVP) and temperature as well as the vapor pressure of different mixtures of propane and butane are correlated as a function of ambient air temperature and propane volume percent. Secondly, the filling losses from storage containers are estimated in percentage of liquid pumped in tanks as a function of working pressure and vapor pressure at liquid temperature. The study showed the proposed method to be in good agreement with the available reliable data in the literature. The average absolute deviation between reported data and the proposed correlation is less than 2%. The proposed simple-to-use approach can be of significant practical value for the process engineers and scientists to have a quick check on the prediction of the displacement losses from storage containers as well as for rapid estimation of vapor pressure of LPG and natural gasoline. (C) 2009 Elsevier Ltd. All rights reserved.