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An olympiad is a span of four (solar or calendar) years. It is the base for some leap rules, the Julian and Gregorian in particular.

Each olympiad contains a single leap day, hence 3 × 365 + 366 = 1461 days in total. Its mean year length is 365.25 days, i.e. 365 days and 8 hours = 2920 h exactly. This is 208 seven-day weeks and 5 days, so the super-cycle with an integer number of weeks runs for 28 years = 10227 days = 1461 weeks.

The modern Olympic (summer) games are held in Julian leap years. Their year number in the Anno Domini count (AD or CE) is divisible by four.

Olympiad or Olympic leap rules have a leap day in every fourth year with possible omissions, e.g. in some centennial years as in the Gregorian and the Revised Julian calendars.

Evenly spread leap rules, such as in the Dee calendar’s 33-year leap cycle, have less jitter, but may be harder to memorize.