Multiphase flow occurs during the production of oil and gas in the wellbores. Modelling and analyzing of this phenomenon is important for monitoring well productivity and designing surface facilities. The ability to estimate and monitor the bottomhole pressure in pumping oil wells when multiphase flow is dominated plays an important role to provide viable information regarding both reservoir and artificial lift performance. Bottomhole pressure estimate becomes more complicated and maybe erroneous when transient multiphase flow conditions occur. Transient multiphase flow in the wellbore causes problems in well test interpretation when the pump is shut off and the well is shut in at surface or sandface and the bottomhole pressure is estimated. In this study, two numerical methods were presented to calculate bottomhole pressure using fluid level measurements by MURAG tool in two deviated pumping oil wells at steady state and transient condition. In the first method, well models were built applying Prosper software, then bottomhole pressure was calculated using fluid level data in Excel employing various assumptions, definitions, and concepts especially for the part of the wellbore occupied with the oil and gas mixture called gaseous liquid column. Required fluid properties for calculations obtained from Prosper models. The second presented method to calculate bottomhole pressure utilized Visual Basic programming in Excel to divide the wellbore annulus into 10-meter intervals. It was programmed to calculate pressure within each individual interval in Prosper using fluid level changes and considering some assumptions. OpenServer was utilized to link the VB-Script (codes) to Prosper for calculations. The outcome of this research led to accurate and reliable calculations of bottomhole pressure by comparing the results with the measured field data and well test interpretations.