Developing a tool to determine the most useful measure of national power

International relations practitioners need a practical way to measure the national power of countries within their interests. Although there are many national power measures, many of them suffer from defects and shortcomings in measuring national power. This study answers the following question: how can the international relations practitioners choose the most useful measure that gives as accurate results as possible? To answer this question, this study has developed a tool to evaluate measures of national power through fourteen criteria and placed the criteria in a measurable matrix using the Decision Matrix Method. The study started with identifying the concept of power and national power in international relations, the importance of measuring national power, and the most prominent challenges facing measuring national power. In addition, the study reviewed the historical phases of measuring national power and reviewing the types of power. Then the study reviewed fifty measures of national power and calculated the frequency of national power variables. Based on this review, the study conducted refereeing with thirty-three experts in six specializations to determine the relative importance of each criterion using the relative importance index (RII) and the five-dimensional Likert scale. Twelve criteria were considered high relative importance by the experts, while only two criteria were considered high to medium importance. This indicates the importance of the criteria developed by the researcher for evaluating measures of national power. The study concluded with a tool for assessing measures of national power, through which it is possible to compare measures of national power in an arithmetic way. Contributions from this study should support practitioners to avoid bias and subjective choices when selecting a measure of national power to use in calculating a state power or comparing the power of two countries, thus leading to more accurate results.