Estimation of gas-initially-in-place GIIP (2P) and remaining gas reserves are a matter of re-examination and very crucial for the oil/gas industry and for the national policy related to energy regulation. There are wide range of reserve estimation method in different sources over time, which has a different range of uncertainty. Reserve means the quantity of gas/oil that is commercially recoverable from known underground hydrocarbon deposit. An existing oil/gas industry needs to know the present reserve of the existing reservoir to take endeavor for further augmentation of field to increase oil/gas productivity. Among several types of reserve estimation method volumetric estimation is easier and done at the early stage of development based on formation factor, well log, fluid saturation and reservoir extent data. Accuracy of this method increases with production data. This project highlights the reserve estimation and remaining reserve calculation of Saldanadi Gas Field one of the prominent and vital gas field for geological situation as the underground reservoir rock is shared by both Bangladesh and India. To calculate reservoir volume using trapezoidal rule and area using planimeter, isopach maps have been created from contour map of both upper and lower gas sand. For greater accuracy production data from the well #1 and well #2 of the field has been used. It is found that total GIIP (2P) from both upper and lower gas sand is 501.186 Bcf among which 350.83 Bcf is recoverable with 70% recovery rate. In addition total remaining reserve is 282.95 Bcf.