This calculator estimates the runout length or anchor trench dimensions required to prevent pullout of the geosynthetics from an anchor trench. The calculator considers three anchor trench configurations: one vertical side, an L-shape, and a U-shape. This calculator solves force equilibrium equations to assess the length of runout, i.e., distance from the slope crest to the front side of the anchor trench or the depth and width of the anchor trench given the available runout length. The calculator includes typical input parameters to conduct sensitivity analyses, such as, allowable geomembrane tensile yield strength and soil backfill properties. The calculator can be used with for reinforced and unreinforced geomembranes.