In this study, we investigate different technologies to measure the specific capacitances C 8 of Nb/Al-AlO x /Nb Josephson junctions. They involve measuring Fiske mode resonance in long Josephson junctions, superconducting quantum interference device (SQUID) resonance, and Josephson plasma resonance. We find a logarithmic relationship between the junction C 8 and its critical current density J c in the range 0.1-2 kA/cm 2 using the Fiske mode resonance method. Our measured C 8 values using SQUID resonance and Josephson plasma resonance are compared with the results obtained by other groups via analyzing the major errors in the C 8 calculation. We discuss the accuracy in evaluating C 8 for all three techniques and suggest using Fiske mode resonance as a relatively stable method for C 8 extraction for the future design of our single-flux quantum circuit.