Interpreting study results is an essential component of decision-making. Both laypeople and healthcare professionals often misinterpret treatment effects that are presented as relative risk reduction. Therefore, we developed and piloted a web-based tool to teach the difference between relative and absolute risk reductions. This project follows the UKMRC-guidance for complex interventions. The tool was developed based on adult learning and design theories. This was followed by a qualitative feasibility study focusing on acceptance, applicability, and comprehensibility with healthcare professionals and laypersons. We conducted think-aloud and semi-structured interviews and analysed them using qualitative content analysis. In addition, we explored calculation skills. Between January 2020 and April 2021, we conducted 22 interviews with 8 laypeople and 14 healthcare professionals from different settings. Overall, the tool proved to be feasible and relevant. With regard to comprehension, we observed an awareness of the interpretation of risk reduction, presented therapy effects were questioned more critically, and the influence of relative effects was recognized. Nevertheless, there were comprehension problems in some of the participants, especially with calculations in connection with low mathematical skills. The tool can be used to improve the interpretation of risk reductions in various target groups and to supplement existing educational programs.