Hebrew Calendar
Adar I 5790

Adar I exists only in a leap year. Seven times in every nineteen years an additional thirty-day month is slotted into the Hebrew calendar between Shevat and Adar, and the year runs to thirteen months instead of twelve. That extra month is Adar I, and Adar II follows it.

It is the one month in the calendar that is, quite literally, an addition. It was not inserted to commemorate something that happened in it; it was inserted so that Nisan would keep landing in spring. Which answers the question most people arrive with: Purim does not fall in this month. The 14th and 15th of Adar I carry only *Purim Katan*, "little Purim": no scroll, no gifts of food, nothing but a small mark left in the place where Purim would sit in an ordinary year.

Why an extra month is needed at all

The Hebrew calendar is trying to satisfy two masters at once. Its months are measured by the moon, each one a full lunar cycle, roughly twenty-nine and a half days. But its festivals are tied to the seasons: Passover must fall in spring, at the barley harvest, and Sukkot at the ingathering.

The problem is pure arithmetic. Twelve lunar cycles come to about three hundred and fifty-four days; a solar year is about three hundred and sixty-five. That is a gap of some eleven days a year; left alone, after three years Passover is running a full month early, and after fifteen it lands in the depths of winter.

This month is the correction. A whole month is added to the year, and every date after it slides back thirty days at a stroke. In the fixed calendar we use today it happens in years known in advance: the 3rd, 6th, 8th, 11th, 14th, 17th and 19th of every nineteen-year cycle. By the end of the cycle the two calendars have returned almost exactly to the same point.

How it was decided, before there was a fixed calendar

All of that is true now. But for centuries nothing was calculated in advance: a panel of sages sat, examined conditions on the ground, and decided during the year itself whether to give it another month.

The baraita lists the three things they judged by: "For three things the year is intercalated: for the spring crop, for the fruit of the trees, and for the equinox. For two of them the year is intercalated; for one of them alone it is not" ¹.

Those three are worth pausing on, because none of them is abstract. "The spring crop" means the state of the barley in the fields: whether it will ripen in time for the omer offering at Passover. "Fruit of the trees" means how far the orchards have come along. "The equinox" is the astronomical reckoning, the vernal point. Two signs out of three were enough; one on its own was not.

In other words, the decision about the extra month was not taken in a book. It was taken in a field.

"The pigeons are still tender": what an announcement looked like

The Talmud preserved one text that makes all of this tangible: the wording of an actual letter dictated by Rabban Gamliel, sitting on a step on the Temple Mount, to the scribe standing in front of him.

Three letters lay before him. Two were routine notices to the Galilee and the south about the deadline for removing tithes. The third went out to the diaspora, to Babylon, to Media, to the rest of the exile communities, and this is what it said: "We inform you that the pigeons are still tender, the lambs are still thin, and the time of the spring crop has not arrived; it seemed right to me and to my colleagues, and I have added thirty days to this year" ².

That is the whole announcement. No formula, no table: three observations and one sentence of decision. And reading it, it is hard not to notice that the extra month in our calendar now looks like a piece of arithmetic, but it began with people looking at lambs.

What actually happens in Adar I

The practical question this month raises is which of the two Adars is the "real" one. The Mishnah answers it with surprising brevity: "The only difference between the first Adar and the second Adar is the reading of the Scroll and gifts to the poor" ³. The one difference is Purim; in everything else the two months rank equally.

Purim Katan (14–15 Adar I). No scroll is read, no food gifts are sent, there is no festive meal, and yet the day is marked. The Shulchan Arukh rules: "On the fourteenth and fifteenth of the first Adar one does not fall on one's face and does not say the psalm 'May the Lord answer you in time of trouble', and eulogies and fasting are forbidden" ⁴. The penitential prayer is skipped; mourning and fasting are off. In his gloss the Rema adds a very human note: some hold one must increase feasting and rejoicing, and we do not follow that, "nevertheless one should add a little to the meal in order to satisfy the stringent opinions", closing with the verse "a cheerful heart has a feast always" ⁵. A slightly better dinner, just in case.

Rosh Chodesh Adar I runs two days, because Shevat always has thirty. Adar I itself also has thirty, so Rosh Chodesh Adar II will likewise be a two-day affair.

And how is the date written? There is a practical ruling for that too. The Rema holds that in legal documents, "when the year is intercalated, in the first Adar one writes simply 'Adar', and in the second, 'Adar the Second'" ⁶. Write "Adar" with no number, and you mean the first.

Common questions about Adar I

When is there an Adar I?
Only in a leap year: seven years out of every nineteen. The grid above shows the month for the year you selected; if that year is not a leap year, there is no Adar I in it at all, only a single Adar.

How many days are in Adar I?
Thirty, always. The Adar II that follows has twenty-nine. Together they add a full month to the year.

Does Purim fall in Adar I?
No. Purim is kept in Adar II. The 14th and 15th of Adar I are *Purim Katan*, which has no scroll reading and no gifts of food: only the omission of the penitential prayer and a ban on eulogies and fasting.

When is Rosh Chodesh Adar I?
Two days: the 30th of Shevat and the 1st of Adar I (3-4/2/30), because Shevat always has thirty days.

What civil month does Adar I fall in?
Usually February, sometimes starting in late January. In a leap year every Hebrew date after it is pushed back thirty days, which is why Passover lands late in such years.

Adar I in the calendar: Hebrew and civil dates side by side

The grid at the top of this page shows Adar I as the Hebrew calendar sees it: the large numerals are the days of the Hebrew month, with the matching civil date printed beneath each one. It is the view that makes visible what a civil calendar hides, that a full thirty days are being inserted into the year here, and that everything after them shifts accordingly.

You can see the two days of Rosh Chodesh at the start, the 14th and 15th, the days of Purim Katan, in the middle, and the end of the month running up to Rosh Chodesh Adar II. The button above the grid prints it to one page, portrait or landscape, without the navigation or this text.

• Every date in the year in one table, and from there each festival's own page: Jewish holidays 2026
• The full printable calendar: printable Hebrew calendar
• For a civil-month view: monthly calendar

Related pages

• February 2030
• March 2030
• The Hebrew month of Adar I 5790