Empirical scaling factors between the height-integrated joule heating rate deduced from measurements of the Chatanika incoherent scatter radar and the square of magnetic perturbation at College are derived. These relationships, calculated for different situations (the eastward and westward electrojects and daytime) are then used to estimate the joule heating rate along the latitudinal extent of the auroral oval on the basis of magnetometer data from the IMS Alaska meridian chain of observations. The total heat input for a disturbed day (April 12, 1978) is estimated to be 2.8¿1015 J.