Zinc–air batteries provide a great potential for future large-scale energy storage. We assess the test factors that mainly affect the measured power density of the zinc–air battery. By fitting the polarization curves of the zinc–air batteries, we reveal the effect of testing parameters (electrode distance, electrolyte concentration, and oxygen flux) and preparation of catalysts ink on the activation, ohm, and concentration polarizations of the zinc–air battery. Finally, recommendations on evaluating the potentials of non-noble-metal electrocatalysts for applications in zinc–air batteries were given.