Delivering an appropriate student workload is important for quality higher education, especially for curriculum design, student well-being and success in studies. Academic credit systems are being increasingly used to determine workload for higher education studies. However, they rely on presumptions about workload, which educational theory and research do not always substantiate. A key example is the European Credit Transfer and Accumulation System (ECTS), which awards credits to students for their academic achievements and the related workload that is measured in study time. This article examines the ECTS from the perspective of its conceptualisation of workload and compares it to earlier research on student workload. Based on a literature review and conceptual analysis, a student workload model is presented and compared to the operating principles of ECTS. In conclusion, ECTS relies on a misleading conceptualisation of student workload with far-reaching implications for higher education research, policy and practice. Recommendations for informed applications and further development of ECTS are presented.