<P> While the Gregorian calendar was implemented in Soviet Russia in February 1918 by dropping the Julian dates of 1--13 February 1918 pursuant to a Sovnarkom decree, the Soviet calendar added five - and six - day work weeks between 1929 and 1940 . Although the traditional seven - day week was still recognized, a day of rest on Sunday was replaced by one day of rest in each work week . Many sources erroneously state that the weeks were organized into 30 - day months from Roman calendar . </P> <P> The Gregorian calendar was implemented in Russia on 14 February 1918 by dropping the Julian dates of 1--13 February 1918 pursuant to a Sovnarkom decree signed 24 January 1918 (Julian) by Vladimir Lenin . The decree required that the Julian date was to be written in parentheses after the Gregorian date until 1 July 1918 . All surviving examples of physical calendars from 1929--40 show the irregular month lengths of the Gregorian calendar (such as those displayed here). Most calendars displayed all the days of a Gregorian year as a grid with seven rows or columns for the traditional seven - day week with Sunday first . </P>

When did russia stop using the julian calendar