The World Calendar is a proposed reform of the Gregorian calendar created by Elisabeth Achelis of Brooklyn, New York in 1930. Features The World Calendar is a 12-month, perennial calendar with equal quarters. Each quarter begins on a Sunday and ends on a Saturday. The quarters are equal: each has exactly 91 days, 13 weeks, or 3 months. The three months in each quarter have 31, 30, and 30 days respectively. Each quarter begins with the 31-day months of January, April, July, or October. The World Calendar also has the following two additional days to maintain the same new year days as the Gregorian calendar. Worldsday The last day of the year following Saturday 30 December. This additional day is dated "W" and named Worldsday, a year-end world holiday. It is followed by Sunday, 1 January in the new year. Leapyear Day This day is similarly added at the end of the second quarter in leap years. It is also dated "W" and named Leapyear Day. It is followed by Sunday, 1 July within the same year. The World Calendar treats Worldsday and Leapyear Day as a 24-hour waiting period before resuming the calendar again. These off-calendar days, also known as "intercalary days", are not assigned weekday designations. They are intended to be treated as holidays. Because any three-month sequence repeats with the same arrangement of days, the World Calendar can be expressed concisely: Background and history The World Calendar has its roots in the proposed calendar of the Abbot Marco Mastrofini, a proposal to reform the Gregorian calendar year so that it would always begin on Sunday, 1 January, and would contain equal quarters of 91 days each. The 365th day of the solar cycle would be a year-end, "intercalary" and optionally holiday. In leap years, a second "intercalary day" follows Saturday, 30 June. Around 1887 French astronomer Gaston Armelin proposed a calendar based on this idea and roughly identical to the World Calendar. Elisabeth Achelis founded The World Calendar Association (TWCA) in 1930 with the goal of worldwide adoption of the World Calendar. It functioned for most of the next twenty-five years as The World Calendar Association, Inc. Throughout the 1930s, support for the concept grew in the League of Nations, the precursor of the United Nations. Achelis started the Journal of Calendar Reform in 1931, publishing it for twenty-five years, and wrote five books on the calendar