Using a unified approach, expressions are derived for the various pole positions and other dipole parameters for the centered and eccentric dipole models of the earth's magnetic field. The pole positions and other parameters are then calculated using the 1945–1985 International Geomagnetic Reference Field Gauss coefficients and coefficients from models of the earth's field for earlier epochs. Comparison is made between (1) the recent pole positions and those pertaining since 1600 and (2) the various theoretical pole positions and the observed dip pole position