Practical guide
Date conversion guide & common questions
Converting a date between the Persian and Gregorian calendars takes seconds — and is easy to get subtly wrong. Here is how conversion works, where people slip up, and how to handle real documents.
How conversion works
Calendars are different ways of naming the same days. To convert a date, a converter turns it into a plain day count, then names that day in the other calendar. Astronomers use exactly such a count, the Julian Day Number: day 2,461,346, for example, is called 10 Aban 1405 in the Persian calendar and 1 November 2026 in the Gregorian one.
Converting to a day count is straightforward for the Gregorian calendar, which follows a fixed rule. For the Persian calendar the hard part is knowing on which day each year begins — that is, which years are leap years. ShamsiDate uses the astronomical leap-year pattern published by Kazimierz Borkowski and tests it day by day against independent implementations; see how Persian leap years work.
Write dates so they can’t be misread
- Put the year first. Write Persian dates as
1405/08/10and Gregorian dates in ISO form,2026-11-01. A date like01/11/2026means 1 November in most countries but January 11 in the United States. - Say which calendar you mean. In English, add “SH” (Solar Hijri) or the word “Shamsi”: 10 Aban 1405 SH. In Persian, شمسی or میلادی removes all doubt.
- Use month names when it matters. 10 Aban 1405 and 1 November 2026 survive copying, translation and different date settings.
- Persian digits are fine — ۱۴۰۵/۰۸/۱۰ and 1405/08/10 are the same date — but some online forms only accept Western digits. The converter’s copy menu offers both.
Common mistakes
Real-life conversions
Birthdays
Convert the full date, not just the year. And if you celebrate by the Persian date, note that its Gregorian day can move by one from year to year. A birthday on 10 Aban fell on 31 October in 2024 but falls on 1 November in 2025 and 2026, because the Persian and Gregorian leap days fall at different points in the year.
Try a birthday: 15 Bahman 1360Iranian documents
Birth certificates (shenasnameh), national ID cards, school and university records, marriage certificates and property deeds are dated in the Shamsi calendar. When you translate or fill in a form, copy the Persian date exactly as written, convert it day by day, and keep the original next to the converted date — for example, 10 Aban 1405 (1 November 2026). The copy menu’s “Both dates” option produces exactly that.
Immigration and international applications
Visa, residence and citizenship applications usually require Gregorian dates, and the same date can appear on many forms. Consistency matters more than anything: convert each date once, check the weekday, and use the same result everywhere. If a certified translation of an Iranian document already shows a Gregorian date, compare it with your own conversion; if they differ, ask the translator to check it before you submit anything.
Academic records
Iranian transcripts and diplomas use Persian dates, and the academic year starts in Mehr (late September). When converting a graduation or enrolment date, convert the exact day shown on the document rather than an approximate month — Persian months straddle two Gregorian ones.
Historical research
For events before 1925, first identify which calendar the source uses. Solar Hijri conversions of earlier dates are proleptic, and Gregorian dates before a country adopted the Gregorian calendar may originally have been recorded in the Julian calendar. ShamsiDate supports 1200–1500 SH (1821–2122 CE).
Frequently asked questions
Is ShamsiDate’s conversion accurate?
Yes, within the supported range. Our test-suite compares every day from 1200 to 1500 SH (1821–2122 CE) with two independent implementations — the widely used jalaali-js library and the ICU Persian calendar built into web browsers — and checks every Nowruz against an independent astronomical calculation of the equinox. All of them agree.
Which dates can I convert?
Any date from 1 Farvardin 1200 to 29 Esfand 1500 in the Persian calendar — 21 March 1821 to 20 March 2122 in the Gregorian calendar. Outside that range the converter tells you so instead of guessing.
Another website gives a result one day different. Why?
Usually because it uses a simplified leap-year rule. The 2,820-year cycle proposed by Ahmad Birashk, still used by some software, disagrees with Iran’s official calendar in a few years: it makes 1404 a leap year instead of 1403, so dates around Nowruz 1404 come out a day off. A plain “every four years” rule fails whenever the five-year gap occurs. Time-zone bugs that turn a date into a timestamp can also shift a result by a day.
Can I convert lunar Hijri (qamari) dates?
Not at the moment. Iran’s official lunar calendar depends on sightings of the new moon, so its dates can’t be computed in advance with the same certainty. We would rather not offer conversions we can’t guarantee.
How do I write a Persian date in English?
Year first with the calendar named — 1405/08/10 SH — or with the month name: 10 Aban 1405. Add the Gregorian equivalent in brackets when the reader needs it: 10 Aban 1405 (1 November 2026).
What do SH, AP and HS mean?
They are abbreviations for the Persian calendar’s era: SH for Solar Hijri, AP for Anno Persico (“Persian year”) and HS for Hijri Shamsi. All three refer to the same calendar.
Does the converter work offline?
Yes. After your first visit, the converter keeps working without a connection, because all calculations happen in your browser.
Sources
- Kazimierz M. Borkowski, “The Persian calendar for 3000 years”, Earth, Moon and Planets 74 (1996): 223–230. doi:10.1007/BF00055188
- ISO 8601, date and time format (International Organization for Standardization). iso.org
- M. Heydari-Malayeri, “A concise review of the Iranian calendar” (2004). arXiv:astro-ph/0409620
Have a date to convert?
Type a Shamsi or Gregorian date — the result appears instantly, right in your browser.