Neutron monitors (NMs), located at different points on the planet, allow us to study the time, energy, and angular characteristics of galactic and solar particle fluxes. Since NMs are located inside Earth's magnetosphere, their response depends on their location on the planet's surface, which can be characterized by the geomagnetic cutoff rigidity. Its calculation depends on the magnetic field model, the date, and even on numerical methods. The paper presents calculated geomagnetic cutoff rigidities at the locations of some neutron monitors and compares the cutoff values with the calculation results obtained by other authors, including a comparison of the time dynamics over the past decade. We show that the geomagnetic cutoff rigidities obtained for 2020 by the IGRF-14 model differ from those derived by IGRF-13; however, for 2015 the difference between the models is negligible. We demonstrate a tendency for the geomagnetic cutoff rigidity to decrease over time, especially at midlatitudes. Comparison of the obtained geomagnetic cutoff rigidities with those obtained by other authors has shown that in most cases the difference does not exceed 0.2 GV. Such discrepancies are significant only in the circumpolar region, where particles are mostly shielded by Earth’s atmosphere rather than by the geomagnetic field. We show that the accuracy of the algorithm in use is comparable to that of other existing instruments and is sufficient for calculating neutron monitor responses.