In order to determine coffee grain moisture during solar drying, Oliveros proposed a direct method called Gravimet based on the weight ratio of coffee in the wash and dry states. The method consists of placing a sample of 200g of clean and healthy coffee in a basket, and recording its weight evolution using a low-cost digital scale. When the coffee weight oscillates between 104 to 105g, its moisture must be between 10 and 12 % (b.h.). To determine the method precision, the standard stove method (ISO 6673) was taken as a reference in 80 drying tests with moisture content between 49 % and 10 % (b.h.). The results indicated that the precision of the Gravimet method varies between 1,92% and 0,09 % (b.h.); the method neither overestimates nor underestimates the moisture content compared to the values determined by the stove. The weight that the sample in the basket must reach to guarantee moisture between 10% and 12% (b.h.) must be between 104 and 105 g and the scale resolution must be 1g. Simultaneous to determining the precision of the Gravimet method, it was also evaluated with 20 coffee growers in five drying tests. In 92 % of the cases the moisture content was between 10 and 12 % (b.h.), with a coffee weight in the basket of 105g.