Sustainability standards are used to assure improved environmental performance in the aquaculture sector. But standard setters face limitations in including a broad range of producers with different capabilities, which in turn reduces their scope and impact. Drawing on Sen's capability approach, we introduce a novel way to assess the extent to which sustainability standards can support the capability of farmers to make prescribed improvements to their production practices. In doing so, we compare four shrimp aquaculture standards (Aquaculture Stewardship Council, Global Aquaculture Alliance, Southeast Asian Shrimp Aquaculture Improvement Protocol and the Thai Agricultural Standard) based on an analysis of what we label the 'prescribed capitals' and 'bundle of capitals' that underpin the compliance capability of producers. The results show that standards narrowly prescribe standards requiring human capital, while there is potential for prescribing a wider bundle of social, financial and physical capitals that can allow more flexible standard compliance. The findings raise the prospect of redesigning sustainability standards to support a broader diversity of producer capabilities and, in turn, increase their overall impact.