Editing Hebrew calendar (section)

===Deficient, regular, and complete years===
The rules of postponement of Rosh HaShanah make it that a Jewish common year will have 353, 354, or 355 days while a leap year (with the addition of Adar I which always has 30 days) has 383, 384, or 385 days.<ref name=companion/>

*A {{transliteration|he|chaserah}} year (Hebrew for "deficient" or "incomplete") is 353 or 383 days long. Both Cheshvan and Kislev have 29 days.
*A {{transliteration|he|kesidrah}} year ("regular" or "in-order") is 354 or 384 days long. Cheshvan has 29 days while Kislev has 30 days.
*A {{transliteration|he|shlemah}} year ("complete" or "perfect", also "abundant") is 355 or 385 days long. Both Cheshvan and Kislev have 30 days.

Whether a year is deficient, regular, or complete is determined by the time between two adjacent Rosh Hashanah observances and the leap year.

A Metonic cycle equates to 235 lunar months in each 19-year cycle. This gives an average of 6,939 days, 16 hours, and 595 parts for each cycle.<ref name=weinberg/> But due to the Rosh Hashanah postponement rules (preceding section) a cycle of 19 Jewish years can be either 6,939, 6,940, 6,941, or 6,942 days in duration. For any given year in the Metonic cycle, the molad moves forward in the week by 2 days, 16 hours, and 595 parts every 19 years. The [[greatest common divisor]] of this and a week is 5 parts, so the Jewish calendar repeats exactly following a number of Metonic cycles equal to the number of parts in a week divided by 5, namely 7×24×216&nbsp;=&nbsp;36,288 Metonic cycles, or 689,472 Jewish years. There is a near-repetition every 247 years, except for an excess of 50 minutes {{frac|16|2|3}} seconds (905 parts).

Contrary to popular impression, one's Hebrew birthday does not necessarily fall on the same Gregorian date every 19 years, since the length of the Metonic cycle varies by several days (as does the length of a 19-year Gregorian period, depending whether it contains 4 or 5 leap years).<ref>[https://outorah.org/p/5696/ Tzarich Iyun: Your Hebrew Birthday]</ref>