Need-based justice is an important ingredient for a pluralistic theory of justice. But how can need-based justice be measured? I will argue that need-based justice cannot be measured by measuring need-satisfaction. This is because need-based justice does not only depend on need-satisfaction, but also on opportunities to avoid or at least mitigate undersupply. Depending on these opportunities, one and the same degree of undersupply can be unjust to different degrees. In this article, I establish a number of desiderata that a measure of need-based justice has to comply with. Resulting measures treat avoidable undersupply as the main source of injustice.
