The paper is devoted to quantitative evaluation of the Old Belief’s prevalence in the Russian empire in the 19th — early 20th centuries. Methodology for updating the official population statistic of Old Believers in the Russian Empire is offered. The verified data on population dynamics of Old Believers is given on the provinces and regions of the Russian Empire and on the state at large. Historiographic thesis about more than tenfold belittling of the number of Old Believers in the official statistic materials of the Russian Empire is refuted. The regional differences in the scale of concealment of faith by Old Believers and in the level of their number falsification by the State government bodies are detected.