A typical indicator for assessing the sustainability of biomass production is resource efficiency that puts the production output in relation to the input of natural resources used for the production. It does, however, not assess the absolute state of resources nor the transgression of sustainability constraints. We propose sustainable resource output (SRO) as an extension of the concept of resource efficiency. To estimate SRO, indicators need to be scaled into a common reference system. For the application of the approach, various indicators were selected covering environmental dimensions of air, water, soil and biodiversity. We demonstrate the applicability of SRO in two case studies with examples from forestry (forest conversion) and agriculture (production systems with increasing intensity). We find that the scaling of indicators plays an important role in the interpretability of SRO. All assumptions, such as scaling thresholds, need to be transparent and consistent between production systems, scenarios, and over time.