Check dams play an important role worldwide in sediment retention, although their effectiveness is currently the subject of debate. In this study, 11 geometric models with their field methodology and equations are proposed to estimate the retained sediment quickly, easily and with a sufficient degree of approximation. The models were applied to a sample of check dams in the Saldaña badlands (Spain) in accordance with the shape of the valley to determine the volume of retained sediment and compare them with other widely used methods. Our geometric method gave lower volumes than topographic methods, but higher volumes than simple methods. This method is thus useful as a first approximation to estimate the sediment trapped by check dams and small silted dams, minimizing fieldwork, calculations and cost. Furthermore, it allows the selection of a better fit to the sediment wedge shape and higher accuracy than the simple methods used until now.