Hebrew Birthday Calculator

DateMath converts the date of birth to the Hebrew calendar with your browser's own Hebrew calendar data, after moving it one day on when the birth was after sunset, since the Hebrew day starts in the evening. For each later Hebrew year, DateMath looks up the same day of the same month: a birthday in Adar of a common year falls in Adar II in a leap year, and a 30th in a month that has only 29 days that year falls on the day after the 29th. Each Hebrew birthday starts at sunset on the evening before the Gregorian date shown.

• The Hebrew calendar. DateMath reads Hebrew dates from the Hebrew calendar data built into your browser (the Unicode CLDR and ICU data every major browser ships). The Hebrew year has 12 months, or 13 in 7 of every 19 years, when Adar I is added before Adar II, and its day starts at sunset. A bar mitzvah is at 13; a bat mitzvah is at 12 in Orthodox communities and often at 13 in others. Source: Hebrew calendar, Bar and bat mitzvah.
• The Gregorian calendar. DateMath treats every date as a Gregorian date, with its leap-year rule: a year divisible by 4 is a leap year, except century years not divisible by 400, so 2000 had a February 29 and 2100 will not. Source: Gregorian calendar.

DateMath's date math is tested against more than 100 cases worked out by hand. Every worked example and table on the site is computed with the same code the calculators run, so a page and its calculator can't disagree.

Your Hebrew birthday is the date you were born on in the Hebrew (Jewish) calendar, such as 16 Heshvan 5787, the Hebrew date of October 27, 2026. Because the Hebrew calendar follows the moon, that date falls on a different Gregorian day each year, so the Jewish birthday calculator gives both: the Hebrew birth date, and the Gregorian date of the Hebrew birthday in the coming years. It works as a Hebrew calendar birthday calculator for any date of birth from 1800 to 2199.

The method, step by step

Born on the evening of March 3, 2014, after sunset:

1. Move the date one day on, because the Hebrew day starts at sunset: the birth belongs to the Hebrew date of March 4, 2014.
2. Convert that day to the Hebrew calendar: 2 Adar II 5774.
3. Find the same Hebrew day and month in each later Hebrew year. In 5787, a leap year, the birthday is on 2 Adar II 5787, Thursday, March 11, 2027, starting at sunset the evening before.

For the birth on the evening of March 3, 2014, the Hebrew birthdays from January 1, 2027 on, with the bar and bat mitzvah years marked:

The Gregorian date moves by up to about a month from year to year and comes back close to the same day after 19 years, the length of the Hebrew calendar’s leap-year cycle.

The Hebrew year starts in the fall with Tishri, the month of Rosh Hashanah. Months have 29 or 30 days, and a leap year adds Adar I before Adar, which is then called Adar II. 5787 is a leap year of 385 days:

The leap years from 5780 to 5798 are 5782, 5784, 5787, 5790, 5793, 5795, 5798: 7 in every 19 years, which keeps the holidays in their seasons.

In a leap year there are two months of Adar. DateMath puts the birthday of someone born in Adar of a common year, or in Adar II, in Adar II, the month in which Purim is kept in a leap year; someone born in Adar I keeps Adar I. In a common year, every Adar birthday is in Adar. Born March 4, 2007, which was 14 Adar 5767:

Customs for Adar I births and for a 30th in a month that has only 29 days that year differ between communities. The calculator takes the day after the 29th in that case; for a bar or bat mitzvah, confirm the date with your rabbi.

A boy becomes bar mitzvah on his Hebrew birthday at 13. A girl becomes bat mitzvah at 12 in Orthodox practice, and at 13 in many Reform and Conservative communities. The table under the calculator marks both years. The celebration, often a Torah reading on a Sabbath, is usually set on or after that date, so the date in the table is where planning starts, not the ceremony itself.

A Hebrew day runs from sunset to sunset, so a child born at 10:00 PM on a Monday was born on Tuesday’s Hebrew date. Tick “Born after sunset” for an evening birth. Sunset depends on the place and the season, so check the sunset time for the place and date of birth when the birth was close to it. Without the time, the date before sunset is the usual default.

For the weekday of a Gregorian date, use the day of the week calculator; for an exact age, the age calculator; and for other special birthdays, the golden birthday calculator. The day countdown counts down to a date from the table.