Several two and three parameter analytical functions were fitted to the measured detection efficiencies () of a Ge detector for a Marinelli beaker filled with samples up to different heights (H). From these, the expression =308E–0.82/((H–6.1)2+107), gave the best fit. The measured and calculated efficiencies were compared and for 70 determinations, a relative standard deviation of only 7.6% was obtained.