Exams have traditionally dominated assessment in higher education. Yet, we still do not know if they are authentic assessment, especially in an environment of rapid demographic changes within higher education and evolving perceptions of authenticity. This work offers a method to measure exam authenticity, defined as the overlap between exams and workplace assignments. To measure the overlap, workplace assignments and exams are mapped into a time-type space. The mapping creates a quantitative measure of exam authenticity. The results show that exams produce vital graduate job market skills. Therefore, they are authentic assessment and a necessary component of the post-pandemic assessment mix. The new authenticity measure is scalable and generalizable across fields and could inform policies and practices, such as subject benchmarking and student recruitment. The paper closes with a simple replication guide.