Biodiversity conservation is an urgent task for our society with special attention for grassland areas. The EU FP7 research project BIOBIO – INDICATORS FOR BIODIVERSITY IN ORGANIC AND LOW-INPUT FARMING SYSTEMS aims at developing scientifically sound, useful and attractive biodiversity indicators for organic and low-input farming in Europe. The Bulgarian case study region in the project is presented by low-input farming in grasslands in the Rhodopi mountains. preliminary selection of 16 low-input farms in Bulgaria for a detailed assessment of biodiversity indicators is carried out. The socio-economic components, environmental factors and partially management intensity have been outlined in order to find farms covering a reliable scale of low-input farming. Three main groups of factors and conditions are implemented for developing an appropriate model for scaling: general socio-economic factors, non-enterprise specific socio-economic conditions, enterprise specific socio-economic conditions. The summarized effect of evaluated factors and conditions is presented by the farm intensity index. The developed model allows preliminary differentiation of farms in three main groups of intensity. A reliable scaling of farms prior to detailed assessment of indicators for biodiversity in low-input grasslands has been confirmed scientifically.