Frequently asked questions

Short, plain answers to the questions people most often ask about converting dates between the Persian (Shamsi/Jalali) and Gregorian (Miladi) calendars. If your question is not here, the guides go into more detail, or you can head straight to the converter.

The calendars

What is the Shamsi (Jalali) calendar?

Shamsi, also called Jalali or Solar Hijri, is the official calendar of Iran. It is a solar calendar whose year begins on Nowruz, the spring equinox, around 20–21 March. Its first six months (Farvardin to Shahrivar) have 31 days, the next five (Mehr to Bahman) have 30 days, and the last month, Esfand, has 29 days, or 30 in a leap year.

What is the Miladi (Gregorian) calendar?

Miladi is the Persian name for the Gregorian calendar, the internationally used civil calendar with months from January to December. "Miladi" refers to dates counted from the birth of Christ, the same as AD/CE. When you convert a Shamsi date to Miladi, you get the everyday Gregorian date.

Using the converter

How do I convert a Shamsi date to Gregorian?

Enter the Persian year, month and day, and the matching Gregorian date appears immediately. There is no submit button and nothing is sent anywhere. For a worked example, see the Shamsi to Gregorian guide.

How do I convert a Gregorian date to Shamsi?

The converter works in both directions at once. Type a Gregorian date and the equivalent Shamsi date is shown alongside it, so you never have to choose a mode. The Gregorian to Shamsi guide walks through it step by step.

How do I convert a birth date?

Enter the birth date exactly as it appears on the document you are working from, in whichever calendar that is. The converter shows the equivalent in the other calendar, which is what most birthdays, passports and certificates need. There is more advice in the birth date guide.

Accuracy and edge cases

Why do time zones not change the result?

The converter uses a date-only model with no clock time attached. Because a calendar date such as 1 Farvardin 1404 maps to a single Gregorian date (21 March 2025) regardless of the hour, there is no timestamp for a time zone to shift. This avoids the classic off-by-one error you get when tools convert a moment in time instead of a calendar day.

How do leap years differ between the two calendars?

Gregorian leap years are years divisible by 4, except centuries not divisible by 400 (so 2000 was a leap year, 1900 was not). Persian leap years follow a different arithmetic pattern, roughly a 33-year cycle, rather than a simple divisibility rule. In a Persian leap year, Esfand has 30 days instead of 29. For example, 1399 was a leap year, so 30 Esfand 1399 exists and equals 20 March 2021. There is a fuller explanation in the leap years guide.

What is the supported date range?

You can convert Jalali years 1 to 1700 and Gregorian years 622 to 2322. A date is treated as valid only when both calendars accept it and its counterpart year also falls inside the supported range, so you cannot accidentally produce a date that does not really exist, such as 31 Mehr.

How is the conversion calculated?

Conversion runs entirely in your browser using the well-established jalaali-js library, which implements the proven 33-year arithmetic cycle, and the result is cross-checked against your browser's built-in Persian calendar. No server is involved in the maths.

Privacy, cost and offline use

Is it free to use?

Yes. The converter is free and there is no account or sign-up.

Is it private?

The converter itself collects nothing, sets no cookies and makes no network call to convert your dates — everything happens locally on your device. Advertising and analytics are optional layers that are switched off by default; they only run if the site owner has configured them and you have given consent, in which case they may load third-party scripts and set cookies. See the privacy and cookies pages for the full picture.

Does it work offline?

Yes. It is an installable progressive web app (PWA). After your first visit the app is cached, so conversions keep working with no internet connection. The offline and install guide covers this in detail.

How do I install it?

Open the site in your browser and use "Add to Home Screen" on mobile, or the install icon in the address bar on desktop, to keep it one tap away and available offline. Step-by-step instructions for each platform are in the install guide.

What are the most common mistakes?

The usual slips are mixing up which calendar a date is written in, forgetting that Esfand has 30 days only in a leap year, and assuming Nowruz always lands on the same Gregorian day when it can be 20 or 21 March. The common mistakes guide lists these and how to avoid them.