Dictionary:Geodetic Reference System 1967 (GRS67)

The gravity field (acceleration of gravity) at the latitude $\lambda$ is given by

$g=978031.846\left(1+0.005278895\sin ^{2}(\lambda )+0.000023462\sin ^{4}(\lambda )\right){\text{mGal}}.$

This gives the correction for latitude as

$1.3049\sin 2\lambda \ \ {\frac {mGal}{mile}}=0.8108\sin 2\lambda \ \ {\frac {MGal}{km}}.$

See also World Geodetic System 1984.