The paper explores standardisation from the perspective of epistemology. Its aim is to enquire into the reality of standards as being very specific tools with defined uses, but at the same time sharing general suppositions about which ends they serve within the realm of science. The paper focuses on the questions how standards relate to ends that facilitate and/or allow for knowledge claims in the sciences. Therefore, scientific practices in different fields of research are assessed, ranging from measurement to experimental trial design in medicine and psychology.