Oil metering is the determination of the quality and quantity of well effluent produced, transferred, delivered or sold. This volume of oil must be measured accurately since it determines the amount paid for oil and gas transaction, royalties and taxes. Measurement of oil and gas, purchases and deliveries is made on a flowing well effluent stream. Hence, flow measurement is paramount in the oil and gas industry. Engineers always check to ensure that the well effluent production rate corresponds with a good reservoir management by flowing the oil and gas well through a choke size that would prevent gas cuspling; this is usually done by monitoring the hydrocarbon well stream flow rate at the flow station after well stream fluid separation. To ensure that the volumetric and flow rate readings obtained from meters are accurate and do not impact negatively on the overall economics and operation of a company, meters have to be proved regularly. This is a procedure required to determine the relationship between the true volumes of well effluent measured by a meter and the volume indicated by the meter. For example an error of only 1.0 % in the measurement of well effluent in a pipeline delivering 300MMcfd of gas and 400 barrels of oil at $1million per year can lead to many losses to either the seller or to the purchaser. Therefore, this study is aimed at modeling a meter factor for proving and calibration of on-line meters. . The developed meter factor model will enhance effective meter factor computation to compensate for temperature, pressure and volume of well effluent and steel in custody transfer units(CTU) based on API standard. inaccurate measurement of well effluent will exposed a company not only to the risk of large financial losses, but also manpower constraints.