The costs factsheet is designed to help data archives understand the range of cost tools available and how they fit together. It uses a tripartite pyramid (Costs Models, Cost Data, “Rules of Thumb”) as a means of understanding existing work, each building on (and requiring the existence of) the other in terms of a knowledge-base, and each requiring different levels of effort. It is intended to be used with other components of the CESSDA Saw Cost-Benefit Advocacy Toolkit to help you understand the approaches and tools available and to support your advocacy to funders and policymakers