Sustainable supply chain governance approaches aim for improvement of environmental and community living conditions at the developing country's side of the global supply chains. Impact evaluation in remote and multiple sourcing countries is hardly done in practice because of its complexity and costs. Evaluating the impact potential with this methodology enables an easier route for assessing and comparing the fast growing number of standard systems. This article describes a methodology for assessing the system performance and impact potential of 'sustainable supply chain governance (SSCG) systems' and uses two cases of certifying sustainable products in the coffee sector (Fairtrade and Utz Certified) for verification of the method. The approach rests on the assumption that a certification system can have substantial impact reduction if it is well organised in its content and organisation: the governance system impact potential (GSIP). Two exemplary pilot cases show that changes made over the years in both systems are directly visible with the methodology and it can be used for monitoring the progress in markets for sustainable products.