Soviet revolutionary calendar

The Soviet revolutionary calendar was in use in the USSR from 1929 to 1940.

Shortly after the Russian Revolution Lenin had decreed to change the calendar in the Soviet Union from the Julian calendar to the Gregorian calendar. This change involved bypassing the days from February 1 till February 13 1918.

Starting on October 1 1929 a new rationalized version of the calendar was introduced. In this version all months had 30 days and the remaining five days were added as holidays in between, not belonging to any month or week. These days were

Lenin day after January 30
Labour Day, two days after April 30
Industry days, two days after November 7
in leap years a leap day after February 30

Also as an anti-religious measure the seven-day week was abolished and replaced with a five-day week, to banish the Christian Sunday as day of rest. Instead all workers were divided into five groups according to colour (yellow, pink, red, purple, green), and each group had one of the remaining weekdays as their day of rest. The intention was to improve industrial efficiency by avoiding the regular interruption of a non-working day.

Although workers had more days off work under the new system (one day in five instead of one day in seven), the separation into five groups made family and social life inconvenient and proved very unpopular. In addition, the projected efficiency gains of the shorter week did not show up in reality.

Starting December 1 1931 the Western schedule of month lengths was restored. The weekly cycle was left in place, but modified to give a common day of rest on every 6th, 12th, 18th, 24th and 30th of the month. The 31st was kept outside this six-day week cycle and varied between a holiday and a working day.

In practice the Sunday rest tradition proved hard to do away with, with workers often taking both Sunday and the new day of rest. Finally, in 1940, the old seven day week was restored.