Biblical Calendar
How We Calculate the Biblical Calendar
This page summarizes the calculation method documented by 119 Ministries. The method begins with the patterns described in Genesis 1 and uses the sun, moon, and stars as timekeeping signs for days, months, years, and YHWH's appointed times.
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The foundational pattern
The 119 Ministries method understands biblical time as beginning in darkness. Days are observed evening to evening, as darkness enters. A new lunar month begins with the dark moon at conjunction.
The sun marks days, the moon marks months, and the annual pattern of the heavens helps establish the year. Jerusalem is used as the reference point for establishing biblical days and months.
The homepage labels its approximation as Estimated nightfall. It uses the evening end of nautical twilight, when the geometric center of the sun is 12 degrees below the horizon. Local conditions may differ. Jerusalem remains the reference for reviewed month and year anchors. Morning light is estimated when the rising geometric solar center reaches 12 degrees below the horizon. A conjunction after that morning point belongs to the coming evening.
Establishing the first biblical month
We determine the first biblical month by selecting the first lunar month whose Passover sacrifice, on the 14th day, falls after the spring equinox. This combines the lunar cycle used for months with the solar season used to keep the spring appointed times in their intended season.
- Determine the actual spring equinox instant in Jerusalem.
- Consider lunar months in chronological order, beginning each with its lunar conjunction.
- If the conjunction occurs during daylight in Jerusalem, the coming evening begins the first day of that candidate month. If it occurs at night, the first day is the biblical day that already began that evening, including when the conjunction falls after civil midnight.
- Count to the daylight portion of day 14 and compare the appointed sacrifice timing in Jerusalem with the equinox instant. Select the first lunar month whose Passover sacrifice falls after that instant.
The comparison concerns the appointed sacrifice on day 14. The opening night of day 14, the beginning of a Gregorian date, and the meal on day 15 are separate boundaries. The precise sacrificial window remains unresolved for close cases; if the equinox falls within that window, the result requires further timing review.
For 2026, the March 19 conjunction occurs at 3:23 a.m. Jerusalem time (01:23 Universal Time), according to the U.S. Naval Observatory. It falls during the night that began March 18. Month one therefore begins at nightfall on March 18, not the following evening. Counting evening to evening places day 14 on March 31 evening through April 1 evening, and days 15 through 21 on April 1 evening through April 8 evening.
Calculating the spring mo’edim
- Determine the actual spring equinox instant in Jerusalem.
- Consider lunar months in chronological order. If a conjunction occurs during daylight in Jerusalem, begin that candidate month that coming evening. If it occurs at night, use the biblical day already begun that evening.
- Count evening-to-evening days to the daylight portion of the 14th day of each candidate month for Passover.
- Select the first lunar month whose Passover sacrifice, during the daylight portion of the 14th day in Jerusalem, falls after the spring equinox. Disclose any unresolved precision in a close boundary case.
- Observe the Feast of Unleavened Bread from the 15th through the 21st day of the first month.
- Identify the weekly Sabbath during Unleavened Bread. The following day is Firstfruits.
- Count Firstfruits as day one of fifty days. Shavuot follows the seventh Sabbath, 49 elapsed days after Firstfruits.
Calculating the fall mo’edim
- Count forward from the first biblical month to the seventh lunar conjunction.
- The first night and day of the seventh month is Yom Teruah (Day of Trumpets).
- The 10th night and day of the seventh month is Yom Kippur (Day of Atonement).
- The 15th through the 21st days of the seventh month are Sukkot (Feast of Tabernacles).
- The 22nd day of the seventh month is the Last Great Day.
From Jerusalem to your city
Our calendar uses Jerusalem as its date line. Each biblical day proceeds westward from there and begins at the selected city’s estimated nightfall. A city’s Gregorian evening date can therefore differ from the Jerusalem reference date. Changing the city recalculates the date and upcoming observances together.
The date stays the same through civil midnight and morning light. It changes at the next qualifying nightfall. If that boundary cannot be calculated, the local biblical date is unavailable and you can choose a Jerusalem reference.
Calculating Hanukkah and Purim
We calculate these biblically referenced traditions from the same reviewed month anchors, using evening-to-evening days and Jerusalem as the reference point.
- Hanukkah begins at the evening starting the 25th day of the ninth month and lasts eight days.
- Purim covers the 14th and 15th days of the twelfth month. We retain month 12 even when a biblical cycle contains a thirteenth month.
Hanukkah and Purim appear separately from YHWH's appointed times and annual rest days. Second-month observances remain under ministry review.
Why the dates are evening to evening
The calculation document consistently treats biblical days as evening to evening. That is why the calendar may show an observance as beginning on the evening before the civil calendar date most people associate with the daytime portion of the observance.
See the calculated dates
Return to the Biblical Calendar to view the calculated calendar cycles from 2025 through 2030.
View the Biblical Calendar