The Hebrew Calendar and Its Months

Two calendars run side by side in Israel, and the Hebrew one is not decorative: it prints on identity cards, school timetables, newspaper mastheads, invitations and gravestones, almost always beside its Gregorian twin. This page covers the months, the mechanism that makes the festivals drift, and the part a learner actually needs — how a Hebrew date is written and how it is said.

The twelve months, in order

The list starts at תשרי, because that is where the year number changes.

Read down the third column and you get a free lesson in prefix vocalisation: בשבט is bi- because שְׁבָט opens on a shva, באדר is ba- because אֲדָר opens on a chataf-patach, and everything else is plain be-. The same three-way split runs through prepositions with place names.

Why the festivals move

Each month begins near a new moon, so it runs 29 or 30 days and twelve of them fall about eleven days short of a solar year. Left alone the calendar would walk backwards through the seasons. Instead a thirteenth month is inserted in seven years out of every nineteen — positions 3, 6, 8, 11, 14, 17 and 19 of the cycle — which is why a common year runs 353–355 days and a leap year 383–385 (Hebrew Wikipedia, הלוח העברי).

The inserted month is אדר א׳, and the ordinary Adar then becomes אדר ב׳, so the extra month goes in before the original and Purim stays in the second one. A leap year is a שנה מעוברת shaná me'ubéret, literally a "pregnant year".

The names are Babylonian, and there is an older set underneath

Every month name above is a loan from Akkadian, brought back by the returning exiles — אִיָּר from ayyāru, and the rest with it — and only some of them turn up in the late biblical books at all. Underneath them the Tanakh keeps fragments of an older Canaanite set, surfacing almost only in the account of Solomon's Temple, where the writing is thick with Phoenician terms:

• יֶרַח זִו — "the second month", 1 Kings 6:1 and 6:37, our אייר
• יֶרַח בּוּל — "the eighth month", 1 Kings 6:38, our חשוון
• יֶרַח הָאֵתָנִים — "the seventh month", 1 Kings 8:2, our תשרי

Note the ordinals those verses attach — seventh for Tishrei, eighth for Cheshvan, second for Iyar. That is the biblical count, which starts at ניסן, and it does not contradict the table above: Nisan is the first month, while Tishrei is where the year number turns over. Only the second fact affects what you write on a form.

The spellings that catch people out

The Academy of the Hebrew Language holds that the month names follow the full-spelling rules, doubling a consonantal vav or yod — so חשוון (a shortened form of מרחשוון, classical חֶשְׁוָן), סיוון (classical סִיוָן) and אייר (classical אִיָּר) all gain a letter. כסלו does not: a word-final consonantal vav is never doubled.

Writing a date, and saying it

Two separate things, and learners collapse them.

Written, a Hebrew date puts the day in letter-numerals: a single letter takes a geresh ׳, two letters take a gershayim ״ between them. The Academy states the rule with its own examples — א׳ באב, י׳ באלול, כ׳ בתשרי, ל׳ במרחשוון with a geresh; י״א באב, ט״ז באלול, כ״ט בנובמבר with gershayim (Academy answer תאריך בחודש, retrieved from a Wayback snapshot of 28 April 2025). The marks themselves are on geresh and gershayim.

Said, there are two live readings and the same Academy answer gives both.

1. The recommended, normative one is a cardinal number in the masculine — אחד בכסלו, עשרה בטבת, שניים ביוני, עשרים ותשעה בנובמבר — and never an ordinal, so not ראשון באפריל and not עשירי בחודש. It is the form the older sources use (תשעה באב, חמישה עשר באב), and it governs Gregorian dates in Hebrew too.
2. In recent generations, the Academy notes, the habit of saying the letter names themselves has taken root: הֵא באייר, כָּף אָלֶף בתמוז, טֵית וָיו באלול. The frozen exceptions are the three names whose letters are said as a word rather than named: ט״ו בשבט and ט״ו באב, read tu, and ל״ג בעומר, read lag.

The year, and the year you are in now

The year is written in letters too, gershayim before the last one: תשפ״ו is 5786, or in full ה׳תשפ״ו with a leading ה׳ for the five thousands, which almost nobody bothers with. It may be read letter by letter or as a pronounceable word — the Academy sanctions both, saying of תש״ף that one may call the year tav-shin-pe and one may call it tasháf.

Because the number turns over at ראש השנה, in תשרי, a Hebrew year straddles two Gregorian ones. תשפ״ו (5786) began on 23 September 2025 and ends on 11 September 2026; תשפ״ז (5787) begins on 12 September 2026 — and it is a leap year, so it will carry an אדר א׳.

Common Mistakes

1. Building 15 out of י and ה. The arithmetic is right and the convention overrides it. י״ה and י״ו are avoided because they spell a name of God, and 15 and 16 are written 9+6 and 9+7 instead.

2. Reading the day as an ordinal. English says the tenth of Tevet, so the ordinal comes out automatically. Hebrew counts the day with a cardinal. The Academy calls the ordinal form non-standard outright, and Hebrew Wikipedia runs 118 : 1 for עשרה בטבת over עשירי בטבת (insource:/…/ regex, three runs, 21 August 2026) — the single hit is a Breslov article naming the fast day, not a date written on anything.

3. Dropping the ב before the month. English puts of between the number and the month and Hebrew puts a prefix on the month, which is easy to lose. Hebrew Wikipedia has ה׳ באייר nine times and ה׳ אייר 0 (same probe and date).

4. Using gershayim on a single letter. The two marks are not interchangeable, and the choice is decided by how many letters the number takes.

Key Takeaways

• Twelve months in an ordinary year, thirteen in a leap year. The order starts at תשרי, because that is where the year number changes.
• אדר א׳ is the inserted month and the ordinary Adar becomes אדר ב׳; seven years in nineteen are leap, which is why the festivals drift against the Gregorian date but never against the season.
• ניסן is the first month by the biblical count and תשרי is where the year number turns over. Both are true; only the second one matters for a date.
• The names are Babylonian loans; the older Canaanite names — זִו, בּוּל, הָאֵתָנִים — survive only in the Temple narrative in 1 Kings.
• Spelling: חשוון, סיוון, אייר double their consonant; כסלו keeps a single final vav.
• Written, the day is letters — geresh ׳ for one, gershayim ״ between two. Said, it is either a masculine cardinal (עשרה בטבת) or the letter names (הֵא באייר), with ט״ו בשבט and ט״ו באב frozen as tu and ל״ג בעומר as lag.
• תשפ״ו is 5786, running from 23 September 2025 to 11 September 2026, after which תשפ״ז — a leap year — begins.