In order to determine optimum size of rangeland properties, range management units within Margha River area, Izeh, were selected and rangeland parts were separated from other types of land use as the study area. Different ecological and socio-economic criteria were used for calculations. Ecological criteria were adopted from range management plans, including forage production, grazing capacity and rangeland condition and trend. Socio-economic criteria were studied conducting a questionnaire-based survey by 62 questionnaires. Also some data about consumptive costs of households were obtained from the data center of Iran Statistics Center. Relative poverty line was calculated in two situations with /without considering the costs and revenues outside the rangeland. Ignoring the costs and incomes related to non-rangeland sources resulted in the optimal size of utilization units to be 146 animal units of sheep or 186 animal units of goats or 62 and 106 animal units of sheep and goats, respectively. Considering all the costs and incomes resulted in the optimal units to be 140 animal units of sheep or 178 goats or 70 and 89 animal units of sheep and goats, respectively. These results could be utilized for range management plans and policies within similar areas.