About ShamsiDate

What ShamsiDate is for

Millions of people move between two calendars every day: Iranians at home and abroad, their families, colleagues, translators, students and researchers. ShamsiDate aims to be the quickest, most trustworthy way to do it. Type or paste a date in either calendar and the other appears instantly — no buttons, no menus and no sign-up.

Principles

• Accuracy first. A converter is only useful if you can trust it, so the calendar engine is tested day by day (see below).
• Speed. Conversion happens instantly on your own device, and the site is built to load quickly even on slow connections.
• Ease. Any common format works — Persian, Arabic-Indic or Western digits, slashes or dashes, month names in English or Persian.
• Privacy. Your dates never leave your browser. There are no ads, and visits are counted with cookie-free Cloudflare Web Analytics. Read the privacy page.

How dates are calculated

Iran’s official calendar is astronomical: each year starts on Nowruz, the day of the March equinox (if it occurs before noon Iran time). ShamsiDate reproduces it with the leap-year pattern published by astronomer Kazimierz Borkowski in 1996, implemented in our own calendar engine.

Before every release, an automated test-suite checks every day from 1 Farvardin 1200 to 29 Esfand 1500 (21 March 1821 to 20 March 2122) against:

• the open-source jalaali-js library, an independent implementation of the same method;
• the ICU Persian calendar shipped with modern browsers and Node.js;
• an independent astronomical calculation of every March equinox in that period, applying the official before-noon rule;
• known Nowruz dates and historical reference dates.

That range is the one ShamsiDate supports. Outside it, the astronomical rule depends on details — the exact definition of noon and long-term changes in Earth’s rotation — that make results less certain, so the converter tells you instead of guessing.

What ShamsiDate does not do

• It doesn’t convert lunar Hijri (qamari) dates, because Iran’s official lunar calendar depends on moon sightings that can’t be computed in advance with certainty.
• It doesn’t show official holidays. Holiday lists are set by the authorities each year, and we prefer not to publish anything we can’t verify.
• Dates before 1925 (1304 SH), when the modern calendar became official, are converted proleptically — with today’s rules.

The logo

The ShamsiDate symbol is a sun with twelve rays — one for each Persian month, clockwise from the top. The six long rays are the 31-day months of spring and summer, the five shorter rays the 30-day months of autumn and winter, and the shortest is Esfand. At the centre, a disk split into day and night marks the equinox, when the Persian year begins.

Guides

Alongside the converter, ShamsiDate publishes a small set of carefully researched guides — to the Persian calendar, the Gregorian calendar, how they differ, Nowruz and converting dates correctly — plus a page of calendar facts. Each guide lists its sources.

Get in touch

Found a date that looks wrong, or have an idea? Use the contact form — we read every message.

Updated: 1 November 2026