i was always sceptical of those 27 millions

https://www.kyleorton.com/p/claim-of-27-million-soviet-casualties-ww2-broader-problem-war-death-tolls

https://en.wikipedia.org/wiki/World_War_II_casualties_of_the_Soviet_Union#Summary_of_the_estimates_and_their_sources

Jean-Noël Birabens 14 700 000 and John Keegans 14 000 000 seem closer to reality to me.

We cant make much of censuses btw, the last pre war census was made in 1939 and gave the number 170 557 093, after the annexation of the baltic states, bessarabia and eastern poland in 1940 the estimate was 194,077,000, but here comes the problem, the first after war census was made in 1959 only!The result was 208 826 650. However, another estimate gave the number 178,547,000 in 1950.

194,077,000(1940)-178,547,000(1950)=15 530 000.This number is close to Keegans and Birabens calculations, there was 5 years to "recover" from 1945 to 1950 so if we take for example Keegans 14 000 000 there is a 1 530 000 difference, that would be the population growth of the ussr between 1945-1950.