To evaluate whether or not a circular product contributes to increase our self-sufficiency, its resource efficiency should not only be claimed without any demonstration, but needs to be measured using existing evaluation methods. Resource efficiency is measured by calculating the resource efficiency ratio, which is the ratio between the benefits from resources and the amount or impact from resource consumption. And even if this definition is clear, several choices still need to be made to calculate this ratio. These choices are subjective but there are four things that project developers should pay special attention to in order to make informed choices, The definition of the numerator, the calculation of the denominator, which resources are covered by your method And the systematic use of resource efficiency indicators during the whole innovation process and not only when the product is finished First, the numerator of the resource efficiency ratio should be carefully defined. It represents the benefits obtained from resources and, in fact, the functionality of your product. It can be done by taking into account the quality and the lifetime of the products. This is the same principle as the definition of the functionality in LCA studies. Secondly, an LCA should always be performed to calculate the denominator of the resource efficiency ratio. As the developer of a new circular product, your aim is to create a product with a solid business plan, but also a product that should contribute to increase the resource efficiency of the economy as a whole. Life cycle thinking is the only approach that allows doing so and should therefore be pursued. On the other hand, gate-to-gate analysis is a limited approach but can be very useful to calculate intermediary indicators and to integrate resource efficiency evaluation all along your project development. Thirdly, you should pay attention to the resource coverage of the method you choose to quantify the resources consumed. As you could read in the previous reading material, each method covers different types of resources. However, lowering the consumption of one specific natural resource can induce higher consumption of another one. At our department, we conducted a study on the sustainability of two valorization pathways for algae grown on aquaculture wastewater: valorization as shrimp feed and valorization as biogas via anaerobic digestion. We compared the results of the resource efficiency ratio when calculating the denominator with different methods: the CEENE method, developed by Ghent University, the ADP method, developed by Leiden University, and the Eco-Indicator 99 method, developed by the consultancy Pré Consultants. These methods do not cover the same resources, and you can see on the figure that choosing one over the other changes the conclusion on which scenario is the most resource efficient. Therefore, we advise to consider one method or a set of methods that cover all resource categories: energy, primary and secondary raw materials, land and water. Finally, integrating resource efficiency consideration more systematically during the course of the product development could help project developers achieve higher resource efficiency goals. One issue is that most project developers evaluate the resource efficiency or even the overall sustainability of their products at the end of the product development and at this stage, the product has already been conceived and there is little room for improvement. So our advise is to implement an iterative resource evaluation process during the product development, starting with preliminary indexes and ending with more elaborate indicators at the end of the project. For simple indicators, gate-to-gate analyses can be conducted as they require less time and data. Along the project, a life cycle thinking approach, which does not imply quantification, should be followed and the full life cycle analysis can be conducted at the end of the project. So an ideal assessment of resource efficiency and the impact of resource consumption that could be universally used in all product development projects does not exist. But if you consider these four advices, you should be able to calculate the resource efficiency of new products and processes in a more scientific and objective way.