A new method is described which allows the accurate absolute calibration of an electron‐spin polarization analyzer. It is based on measuring spin–orbit‐induced scattering asymmetries and simultaneous polarization analysis of the scattered electrons in elastic electron scattering. It is shown how the effective Sherman function of a classical high‐energy Mott detector can be determined easily to within better than ±2%. The method is applicable to other types of electron‐spin polarization detectors as well.