Magnetohydrodynamic pumps with permanent magnets are a promising technology for liquid metal transportation using the electromagnetic interaction between an electrically conducting fluid and a magnetic field. This paper presents a numerical 3D magnetic field distribution which is compared with an experimentally measured magnetic field mapping in the liquid metal (Na) channel. With a solid body approximation, this data is further used to calculate the pump pressure-flowrate characteristics by an electrodynamic approach. Agreement was obtained with the measured pressure-flowrate characteristics when testing an electromagnetic pump prototype. The test was conducted in the newly designed sodium loop at the Institute of Physics of the University of Latvia (IPUL).