The characterization of pyroelectric materials is essential for the design of pyroelectric-based devices. Pyroelectric current measurement is the commonly employed method, but can be complex and requires surface electrodes. Here, we present noncontact electrostatic voltmeter measurements as a simple but highly accurate alternative, by assessing thermally-induced pyroelectric surface potential variations. We introduce a refined model that relates the surface potential variations to both the pyroelectric coefficient and the characteristic figure of merit (FOM) and test the model with square-shaped samples made from PVDF, LiNbO₃ and LiTaO₃. The characteristic pyroelectric coefficient for PVDF, LiNbO₃ and LiTaO₃ was found to be 33.4, 59.9 and 208.4 $\mu$C m${}^{-2}$ K${}^{-1}$, respectively. These values are in perfect agreement with literature values, and they differ by less than 2.5% from values that we have obtained with standard pyroelectric current measurements for comparison.