The Calendar
Pick any year between 1001 BCE and 3000 CE. The calendar gives the moon phases, the equinoxes and solstices, and the appointed days that follow from them — with the weekday, the sunset that opens each day, and the date in both the Julian and the Gregorian reckoning.
Meeus Almanac
New moons, full moons, equinoxes, solstices and the biblical feast days for any year from 1001 BCE to 3000 CE — with the weekday, the sunset that opens each day, and the date in both the Julian and the Gregorian calendar.
Feast days
| Holy convocation | Feast | Date | Weekday | Gregorian calendar | Julian calendar | Begins | Ends |
|---|
Events
| Event | Date | Weekday | Gregorian calendar | Julian calendar | Time UT |
|---|
The feast days
The feast dates follow the rule set given for this calendar, not any rabbinic or modern reckoning. Every day runs from sunset to sunset, so each feast begins at the sunset of the previous evening.
Two places are at work, and they are not the same one. The calendar is reckoned at Jerusalem, always: it is the sunset there that decides whether a new moon falls before or after a day boundary, and so which day carries which date. Moving the observer does not move a single date. What the observer sets is where you are standing — and that decides at what moment the day you have been told about actually opens and closes for you. The two sunset columns are computed for that place from Meeus chapters 12, 15, 22 and 25, and are shown on your own clock; for years outside the age of time zones they fall back to local mean solar time, and the line under the table says which of the two you are looking at.
Every month begins at the new moon. By rule 1, month I is the lunation that holds the first full moon after the March equinox — so that full moon lands on the 14th or 15th, at Passover, and the first day of month VII is a new moon as rule 7 requires. Pesach is the 14th, the Feast of Unleavened Bread runs from the 15th to the 21st, and the Day of Firstfruits is whichever of those days has its daylight half on a Sunday, so it always runs from sunset on Saturday to sunset on Sunday. The Feast of Weeks is 49 days later, again Saturday sunset to Sunday sunset. The Day of Trumpets, the Day of Atonement and Tabernacles fall on the 1st, the 10th, and the 15th to the 22nd of month VII.
Month I usually begins before the equinox: the rule asks that the month contain the first full moon after it, not that it start after it.
“New moon” here means the astronomical conjunction, the moment the Moon passes the Sun and is invisible. Counted from that instant, the full moon of month I falls on the 16th in 1860 of the 4001 years covered, the 15th in 1538, the 17th in 582 and the 14th in only 21 — that is, a day or two after Pesach on the 14th. A calendar that instead opens the month at the first visible crescent, one to two days after conjunction, moves the whole month later and brings that full moon back onto the 14th or 15th. Which of the two you mean changes every date on this page by a day or two.
In 64 of the 4001 years covered, the first full moon follows the March equinox by less than half a day; the page flags those, because a marginally different reading of “after the equinox” would move the entire year one lunation on.
How these dates are computed
Moon phases follow chapter 49 of Astronomical Algorithms: the mean phase from the lunation number k, then 25 periodic terms in the Sun's mean anomaly M, the Moon's mean anomaly M′ and its argument of latitude F, plus 14 planetary corrections. Equinoxes and solstices follow chapter 27 — table 27.A for years up to +1000, table 27.B after that, corrected by the 24 periodic terms of table 27.C.
The algorithms yield Dynamical Time. Times shown here are Universal Time, obtained by subtracting ΔT from the polynomial expressions of Espenak & Meeus, the standard extension of chapter 10 back to −500. ΔT grows from about a minute in 1900 to roughly 4¾ hours in 500 BCE, so it dominates every ancient date on this page.
Year numbering is astronomical: year 0 is 1 BCE, year −500 is 501 BCE. Before 15 October 1582 the Julian column is the date as it would actually have been written and the Gregorian column is proleptic; from that date on it is the other way round. The civil column is the darker one. The weekday is unbroken across the 1582 reform — it is derived from the Julian Day number itself.
Expect the moon phases to be good to about a minute for recent centuries and to a few minutes in antiquity; equinoxes and solstices to well under a minute after +1000 and within about a minute before it. The uncertainty in ΔT itself — tens of minutes at 500 BCE — is far larger than either.
How the dates are reached
The astronomy is Jean Meeus, Astronomical Algorithms (2nd edition): chapter 49 for the phases of the moon, chapter 27 for the equinoxes and solstices, chapter 7 for the Julian Day and the weekday, and chapters 12, 15, 22 and 25 for sunset at Jerusalem. Those give Dynamical Time; the times shown are Universal Time, reached by subtracting ΔT from the polynomial expressions of Espenak and Meeus.
ΔT is not a detail. It is about a minute in 1900 and roughly four and three-quarter hours in 500 BCE — the accumulated drift between the Earth’s rotation and uniform time. For an ancient date it moves the answer further than anything else in the calculation.
Where the day begins
Everything on this page hangs on one choice: a day begins at sunset, not at midnight. That choice is not mine. It stands in the text, and in four ways at once — the first of which can simply be counted out.
As arithmetic. Two commands are about the same feast, and they have to agree. Leviticus says which days it is:
And on the fifteenth day of the same month is the feast of unleavened bread unto the Lord: seven days ye must eat unleavened bread. Leviticus 23:6
So the feast runs from the fifteenth through the twenty-first. Exodus says when the eating starts and stops:
In the first month, on the fourteenth day of the month at even, ye shall eat unleavened bread, until the one and twentieth day of the month at even. Exodus 12:18
Count it. If the day begins at evening, then “the fourteenth day at even” is the moment the fifteenth begins, and “the one and twentieth at even” is the moment the twenty-first ends. Between them lie exactly seven days: the fifteenth through the twenty-first. The two commands then say the same thing.
If the day began in the morning, “the fourteenth at even” falls in the middle of the fourteenth — a day early by Leviticus — and the eating stops half a day early as well. The two commands then contradict each other at both ends. There is only one reckoning on which they fit.
As a dating. At the Day of Atonement the turn of the day is not merely stated; it is used to date a day.
It shall be unto you a sabbath of rest, and ye shall afflict your souls: in the ninth day of the month at even, from even unto even, shall ye celebrate your sabbath. Leviticus 23:32
The Day of Atonement is the tenth of the month (Leviticus 23:27). Here it is dated from the evening of the ninth. That is only a correct dating if the evening of the ninth already belongs to the tenth.
In use. Where the text shows people watching the clock, they are watching the sun. Nehemiah has the gates of Jerusalem shut as soon as it begins to grow dark, before the sabbath (Nehemiah 13:19) — too early, if the sabbath only began the next morning. And at Capernaum a crowd waits for the sun:
And at even, when the sun did set, they brought unto him all that were diseased, and them that were possessed with devils. Mark 1:32
They waited because it was the sabbath and they could carry nothing; at sunset it was over. On the other side of that same boundary stands Luke: it is the preparation day, and while Joseph takes the body down “the sabbath drew on” (Luke 23:54). One sabbath goes out at sunset; the other comes in.
And in the creation account. The best-known passage comes last, and deliberately so.
And God called the light Day, and the darkness he called Night. And the evening and the morning were the first day. Genesis 1:5
That sentence returns at every day of creation: evening, then morning, then the day counted. It fits the evening reckoning, and it has been read that way from antiquity. But it can also be read as a closing formula — the work is done in the light, and then an evening and a morning pass. In the same verse, moreover, the light half is called Day and the dark half Night, so the word is doing two jobs there.
That is why Genesis stands at the bottom here and not at the top. It fits the reckoning; it does not settle it. What settles it are the commands above, and those can be counted out.
The rules the feasts follow
So every day runs from sunset to sunset, and each appointed day begins the evening before the date shown. Every month begins at the new moon. Month I is the lunation that contains the first full moon after the March equinox — so that full moon falls at Passover, and the first day of the seventh month is a new moon.
The text does not use one word for these days but four, and they do not say the same thing. The table keeps them apart.
Appointed time: the Hebrew mo’ed, which the King James renders the feasts of the Lord. This is the umbrella word: Leviticus 23:4 gathers every day of the chapter under it — Passover and the Day of Firstfruits included, which are days of work.
Holy convocation: miqra qodesh, a gathering called out. Seven days in the year carry that name, and they are the same seven that the menorah on the front page counts.
Sabbath rest: shabbaton. This comes on top of the holy convocation, and stands only at the Day of Trumpets (Leviticus 23:24) and at the first and the eighth day of the Feast of Tabernacles (Leviticus 23:39).
High sabbath: shabbat shabbaton, the heaviest designation of all. In this chapter it falls twice only: on the weekly sabbath (Leviticus 23:3) and on the Day of Atonement (Leviticus 23:32). That day is therefore set level with the sabbath itself. The word high is not from Leviticus but from John 19:31, where that day is called an high day.
Three days in the table carry no rest designation at all: the new moon the year opens with, Passover, and the Day of Firstfruits. That is not an omission. On those three something is done — the moon seen, the lamb killed, the sheaf waved — rather than rested.
Passover falls in the afternoon of the fourteenth, before sunset. The Day of Firstfruits and the Feast of Weeks both run from sunset Saturday to sunset Sunday, since both are the day after a sabbath.
The first row falls outside the year and stands there for comparison. Leviticus 23 opens with it, before any of the feasts, and gives it exactly the two designations the Day of Atonement gets further down.
| Day | When | Holy convocation | Rest |
|---|---|---|---|
| Weekly sabbath | Leviticus 23:3 | high sabbath — Leviticus 23:3 | |
| First Day of the Year | I 1 | — | — |
| Pesach | I 14 | — | — |
| Feast of Unleavened Bread | I 15 – I 21 | days 1 and 7 — Leviticus 23:7-8 | — |
| Day of Firstfruits | within I 15 – I 21 | — | — |
| Feast of Weeks | 49 days later | Leviticus 23:21 | — |
| Day of Trumpets | VII 1 | Leviticus 23:24 | sabbath rest — Leviticus 23:24 |
| Day of Atonement | VII 10 | Leviticus 23:27 | high sabbath — Leviticus 23:32 |
| Feast of Tabernacles | VII 15 – VII 22 | days 1 and 8 — Leviticus 23:35-36 | sabbath rest on both — Leviticus 23:39 |
Spring and autumn
Everything above can be computed. What follows cannot: it is a reading of the festival calendar which many expositors follow, and it stands here as a reading and not as a result.
The appointed times lie in two groups with an empty summer between them. The first runs from Pesach through the Feast of Weeks, the second from the Day of Trumpets through the Feast of Tabernacles. On this reading the spring days point to the first coming of Yeshua (Jesus) and the autumn days to his return as king. The menorah on the front page shows the same division: of the seven holy convocations, three stand in the spring and four in the autumn.
What keeps the two groups apart is not the interpretation but the timing. Of the spring days the New Testament itself says that something was fulfilled in them, and it names the day when it does:
| Day | What the day is in Leviticus | Where the New Testament takes it up |
|---|---|---|
| Pesach | the lamb killed in the afternoon of the fourteenth (Leviticus 23:5) | 1 Corinthians 5:7 |
| Unleavened Bread | seven days without leaven (Leviticus 23:6-8) | 1 Corinthians 5:7-8 |
| Day of Firstfruits | the first sheaf waved, the day after the sabbath (Leviticus 23:10-11) | 1 Corinthians 15:20-23 |
| Feast of Weeks | fifty days later, two loaves waved (Leviticus 23:15-17) | Acts 2:1-4 |
With the autumn days it is otherwise. There Leviticus describes the day and the New Testament takes up its imagery — but nowhere does it say that the day itself has been fulfilled:
| Day | What the day is in Leviticus | Where the imagery returns |
|---|---|---|
| Day of Trumpets | a memorial of blowing, the first of the seventh month (Leviticus 23:24) | 1 Corinthians 15:52; 1 Thessalonians 4:16 |
| Day of Atonement | the one day on which the high priest went behind the veil (Leviticus 16; 23:27-32) | Hebrews 9:24-28 |
| Feast of Tabernacles | seven days dwelling in booths, and an eighth day (Leviticus 23:34-43) | Zechariah 14:16-19; Revelation 21:3 |
That difference is the whole of what carries this reading, and it is worth holding to: the first group is tied in the text itself to an event, the second is not. Colossians 2:16-17 calls these days a shadow of things to come — a shadow of something that has been, and of something still ahead.
None of this changes the calendar above. That computes the days; what they mean lies outside it.
And the new moon?
It is not in the list in Leviticus 23. The chapter names the sabbath and seven yearly days, and the monthly new moon is not among them. In most other places it is set beside them rather than counted under them: in the sabbaths, in the new moons, and on the set feasts (1 Chronicles 23:31) — three things in a row, and the same in Numbers 10:10 and Isaiah 1:14.
But in one place the opposite happens:
And it shall be the prince’s part to give burnt offerings, and meat offerings, and drink offerings, in the feasts, and in the new moons, and in the sabbaths, in all solemnities of the house of Israel: he shall prepare the sin offering, and the meat offering, and the burnt offering, and the peace offerings, to make reconciliation for the house of Israel. Ezekiel 45:17
Look at the fourth expression. In Hebrew it carries no and: it is not a fourth kind beside the three before it but a summing up of them. The feasts, the new moons and the sabbaths together are all the appointed times of the house of Israel. There the new moon does fall under the appointed times. Hosea 2:11 does much the same, though there an and is present.
There is a second reason to count it in, and nobody disputes this one: one new moon is named in Leviticus 23 after all, the one of the seventh month. The Day of Trumpets is a new moon and an appointed time at once.
That the new moon was a day on which something happened is beyond doubt. An offering belonged to it (Numbers 28:11), it was blown upon (Numbers 10:10), and in ordinary speech it stands beside the sabbath: it is neither new moon, nor sabbath (2 Kings 4:23).
In short: in the narrow sense of Leviticus 23 the new moon is not an appointed time; in the wide sense of Ezekiel 45:17 it is. The table above keeps to the narrow list, because that is what fixes the seven holy convocations. But the month the new moon opens fixes all seven of them.
Where it is uncertain, and why
Two places, and both are worth knowing about before you rely on a date.
The borderline years. In 64 of the 4,001 years covered, the first full moon follows the March equinox by less than half a day — in one case by fifteen minutes. A marginally different reading of “after the equinox” moves the whole year one lunation on. Those years carry a warning on the table above rather than a silent answer.
Conjunction or crescent. The new moon here is the astronomical conjunction, the moment the moon passes the sun and is invisible. Counted from that instant, the full moon of month I falls on the 16th in 1,860 of those years, on the 15th in 1,538, on the 17th in 582 and on the 14th in only 21 — a day or two after Pesach on the 14th. A calendar that instead opens the month at the first visible crescent, one or two days after conjunction, moves everything later and brings that full moon back onto the 14th or 15th. Which one you mean changes every date on this page.