The article is devoted to laying out methodological foundations for assessing the level of inflation in modern Russia. It justifies using aggregate (integral) indices to characterize price processes and determine strategic development priorities.The use of inflation indicators used in the international practice in Russia does not provide the necessary level of reliability of information about the ongoing inflationary processes in various sectors of the national economy. It does not allow us to objectively assess the current state of socio-economic development to timely capture and account for changes in the trends of strategic development. As a result, the quality of analytical work, first and foremost carried out by real sector development institutions, is reduced, which affects the effectiveness of decisions made by economic entities and public administration bodies.The authors argue that the aggregate inflation index shows a higher degree of variability in the dynamics of inflationary processes than the consumer price index since it accounts for changes in the most significant sectors of the economy, the social sphere and the financial sector.The article proposes an improved method for constructing an aggregate inflation index based on mathematical and statistical methods. It is shown that the use of an aggregated inflation index increases the objectivity of the assessment of economic growth and social progress, which makes it possible to more quickly predict the dynamics of costs and results with a sufficiently high degree of forecast accuracy.The need for regular adjustment of the composition of private indicators taken into account in the formation of the aggregate inflation index is justified by including new, more relevant indicators and excluding those that have lost their relevance.Results of the study are the conclusions obtained by analyzing the dynamic series of aggregate and partial inflation indices formed on the basis of the methodology proposed by the authors.