Leap year vernal equinox moves a day earlier in the calendar about every 131 years. The Revised Julian calendar adds an extra day to February in years that are multiples of four, except for years that are multiples of 100 that do not leave a remainder of 200 or 600 when divided by 900. This rule agrees with the rule for the Gregorian calendar until 2799. The first year that dates in the Revised Julian calendar will not agree with those in the Gregorian calendar will be 2800, because it will be a leap year in the Gregorian calendar but not in
Chinese calendar solstices, is divided into 24 solar terms. Different versions of the traditional calendar might have different average solar-year lengths. One solar year of the 1st century BC Tàichū calendar is (365.25016) days. A solar year of the 13th-century Shòushí calendar is (365.2425) days, identical to the Gregorian calendar. The additional .00766 day from the Tàichū calendar leads to a one-day shift every 130.5 years. Pairs of solar terms are climate terms, or solar months. The first solar term is "pre-climate" (), and the second is "mid-climate" (). There are generally 11 or 12 complete months, plus two incomplete months around