Inclusive, safe, resilient and sustainable cities are included in Sustainable development Goals. The choice between environmental and social well-being is a very acute issue. It is necessary to take into account the interaction of three city dimensions: economic, ecological and social. The aim of the paper is to evaluate externalities in terms of population for 114 Russian cities all over the country considering all three dimensions.

The methods are the analysis of statistical data by econometric methods and their processing including geographical visualization. The data was taken from the Federal State Statistics Service database. The main results are the followings. The methodology for evaluation of externalities and estimation a hypothetical «efficient city size» in terms of population for Russian cities has been elaborated. The access to high-paying jobs and the availability of social benefits is often associated with living or moving to cities or regions with an unfavorable environment. Some cities feature an extremely high growth rate, dense population and often a low level of management and economic development.

Then there was demonstrated how to achieve a hypothetical «efficient city size» by means of environmental management and changes in city area. This should be helpful in achieving the Sustainable Development Goals (especially the Goal 11) and some targets mentioned in the «New Urban Agenda». It is essential to pay attention to the function of a city and its spatial organization. Some other measures to rise efficiency were proposed as well.