Helmholtz coils are regularly utilised for various extremely low frequency (ELF) bioelectromagnetic experiments. The evaluation was conducted for the Helmholtz coil magnetic field frequency and uniformity, characterised by frequency-domain and geometric ELF magnetic exposure characteristics. An established approach which consisted of the mathematical calculations of the geometric parameters, computational modeling, and experimental development measurements of the Helmholtz coil's magnetic field frequency and uniformity, improved the quality of magnetic field uniformity and minimised the magnetic field intensity losses.