It is possible to see convergent conical type nozzles everywhere, from daily life to rocket science. They are utilized as the main part of the propulsion system in many applications such as air blow guns for spraying, steam turbines for compression, rockets for thrust generation, satellites for altitude control and so on. Although the convergent conical nozzle is a well-known nozzle, there are few studies on the effects of geometric changes by comparing more than one approach together. Therefore, this study investigates thrust and volumetric flow rate for different inlet and exit diameters of the convergent conical nozzles theoretically, numerically and experimentally. In this study, the quasi-one-dimensional Euler equations are defined for the theoretical investigation of convergent conical nozzles. However, in this approach, many important features such as viscous losses are neglected. In fact, nozzle flows have highly complex features including shock waves, turbulence, and boundary layers due to compressible effects. Thus, Computational Fluid Dynamic (CFD) simulations are performed with ANSYS Fluent for numerical investigation of the nozzle in this study. CFD simulations provide a better understanding and illustration of convergent conical type nozzle flows. For a third approach, the experimental investigation is conducted for thrust and volumetric flow rate measurements. Theoretical and numerical results are compared with the experimental results and similarity ratios are defined to find the closest to the experimental results.