The Olympiad Calendar with Smoothly Spread Month Lengths is a four year calendar of months having 30 or 31 days, the lengths of which are evenly distributed over the four years. The months form two cycles, one long 9 month cycle of 30-31-30-31-30-31-30-31-30 or 274 days, and one short 7 month cycle of 30-31-30-31-30-31-30 or 213 days, forming a joint cycle of 487 days. Three such joint cycles have 1,461 days, which is the exact number of days in a typical four year solar Olympiad. The names of the months switch throughout the year according to the length of that month in a particular year.