The Soviet calendar was a modified Gregorian calendar that was used in Soviet Russia between 1918 and 1940. Several variations were used during that time.
The Gregorian calendar, under the name "Western European calendar", was implemented in Soviet Russia in February 1918 by dropping the Julian dates of . As many as nine national holidays (paid days of rest) were implemented in the following decade, but four were eliminated or merged on , leaving only five national holidays: 22January, 1–2May, and 7–8November until 1951, when 22January reverted to a normal day.
During the summer of 1929, five-day continuous work weeks were implemented in factories, government offices, and commercial enterprises, but not collective farms. One of the five days was randomly assigned to each worker as their day of rest; the purpose of this system was to allow factories to operate every day, always having most of its workers present to maintain production. These five-day work weeks continued throughout the Gregorian year, interrupted only by the five national holidays. While the five-day week was used for scheduling work, the Gregorian calendar and its seven-day week were used for all other purposes. All surviving examples of physical calendars from 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 (Воскресенье; "Resurrection") first.
thumb|upright=1.1| Soviet pocket calendar, 1931 <br/> Numbered five-day work week, excluding five national holidays
The 1931 pocket calendar displayed here is a rare example that excluded the five national holidays, enabling the remaining 360 days of the Gregorian year to be displayed as a grid with five rows labeled for each day of the five-day week. Even it had the full Gregorian calendar on the other side.
Work weeks
During the second half of May 1929, Yuri Larin (Юрий Ларин, 1882–1932) proposed a continuous production week (nepreryvnaya rabochaya nedelya = nepreryvka) to the Fifth Congress of Soviets of the Union, but so little attention was paid to his suggestion that the president of the Congress did not even mention it in his final speech. By the beginning of , Larin had won the approval of Joseph Stalin, prompting all newspapers to praise the idea. The rationale was that while workers needed rest, machines did not; therefore, scheduling workers' days off in such a way as to maintain factories constantly in operation would make it possible to produce more for less time. In addition, the change was advantageous to the anti-religious movement, as Sundays and religious holidays became working days. On the Supreme Economic Council of the RSFSR directed its efficiency experts to submit within two weeks a plan to introduce continuous production. Before any plan was available, during the first half of , 15% of industry had converted to continuous production according to Larin, probably an overestimate. On the Council of People's Commissars (CPC) of the Soviet Union (Sovnarkom) declared "it is essential that the systematically prepared transition of undertakings and institutions to continuous production should begin during the economic year ". The lengths of continuous production weeks were not yet specified, and the conversion was only to begin during the year. Nevertheless, many sources state that the effective date of five-day weeks was which was the beginning of the economic year. But many other lengths of continuous work weeks were used, all of which were gradually introduced.
Implementation of continuous production weeks
Specific lengths for continuous production weeks were first mentioned when rules for the five-day continuous work week were issued on . On building construction and seasonal trades were put on a continuous six-day week, while factories that regularly halted production every month for maintenance were put on six- or seven-day continuous production weeks. In , it was reported that about 50 different versions of the continuous work week were in use, the longest being a 'week' of 37 days (30 continuous days of work followed by seven days of rest). By the end of 1929, orders were issued that the continuous week was to be extended to 43% of industrial workers by and to 67% by . Actual conversion was more rapid, 63% by . In it was decreed that the conversion of all industries was to be completed during the economic year , except for the textile industry. But on peak usage was reached, with 72.9% of industrial workers on continuous schedules. Thereafter, usage decreased. All of these official figures were somewhat inflated because some factories said they adopted the continuous week without actually doing so. The continuous week was applied to retail and government workers as well, but no usage figures were ever published.
The continuous week began as a five-day cycle, with each day color-coded and marked with a symbol. The population would be carved up into as many groups, each with its own rest day. These circles indicated when you worked and when you rested.
Implementation of six-day weeks
As early as May 1930, while usage of the continuous week was still advancing, some factories reverted to an interrupted week. On , one of the largest factories in the Soviet Union was put on an interrupted six-day week (Шестидневка = shestidnevka). On , Stalin condemned the continuous work week as then practiced, supporting the temporary use of the interrupted six-day week (one common rest day for all workers) until the problems with the continuous work week could be resolved. During , most factories were put on an interrupted six-day week as the result of an interview with the People's Commissar for Labor, who severely restricted the use of the continuous week. The official conversion to non-continuous schedules was decreed by the Sovnarkom of the USSR somewhat later, on . Institutions serving cultural and social needs and those enterprises engaged in continuous production such as ore smelting were exempted. It is often stated that the effective date of the interrupted six-day work week was