  The effective measurement heights of the fountain and the release types of
atom gravimeters have been determined using the description of the instruments
as linear time-invariant (LTI) system. The distance from the initial position
of the atoms to the locus of the effective measurement height is expressed as
simple fraction of the total trajectory length. Leaving the measured gravity
for reporting at the effective measurement height allows to eliminate the
gradient from calculations and avoid up to 1 $\mu$Gal of its uncertainty added
to the instrument error budget.
