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Notes on time, calendars, and dates: how the Persian (Jalali / Shamsi) and Gregorian systems work, where they disagree, and how to convert between them with confidence.
All postsهمه نوشتهها
- Calendarsتقویمها
Convert Jalali to Gregorian in code (JS & Python)
How to convert Jalali (Shamsi) dates to Gregorian in JavaScript and Python, which libraries to use, and the edge cases to test so your conversions stay correct.
- Leap yearsسالهای کبیسه
30 Esfand: the day that only exists in leap years
Why 30 Esfand appears only in Persian leap years, how it mirrors 29 February, and how to tell whether a 30 Esfand date is valid for a given year.
- Calendarsتقویمها
Shamsi and Gregorian conversion, explained
A complete guide to converting between the Persian (Shamsi / Jalali) and Gregorian (Miladi) calendars: the year offset, month lengths, leap years, and pitfalls.
- Nowruzنوروز
What is Nowruz? Dates, the equinox, and traditions
Nowruz is the Persian New Year, marking the spring equinox on 20 or 21 March. What it is, why the date moves, and the traditions like the haft-sin table.
- Age & birthdaysسن و تولد
How old am I in the Persian calendar?
Work out your age in the Persian (Shamsi) calendar, why it can differ by a year from your Gregorian age, and how to get the exact number in seconds.
- Calendarsتقویمها
Gregorian to Shamsi: convert any date the easy way
How to convert a Gregorian (Miladi) date to the Persian (Shamsi / Jalali) calendar, the quick rule for the year, and why converting beats doing it by hand.
- Two calendarsدو تقویم
Is the Persian calendar lunar or solar?
The Persian (Shamsi) calendar is solar, tied to the spring equinox, not lunar. Here is how it differs from the lunar Islamic (Hijri) calendar.
- Calendarsتقویمها
What year is it in the Persian calendar right now?
The current Persian (Shamsi) year is 1404, rolling to 1405 at Nowruz. Here is why it is ~621 years behind the Gregorian year, and how to convert any year.
- Calendarsتقویمها
Today's date in the Persian (Shamsi) calendar
What today is in the Persian (Shamsi / Jalali) calendar, how to read it, and how to convert any Gregorian date to the Iranian calendar in one step.
- Two calendarsدو تقویم
Gregorian vs Solar Hijri: two calendars on one timeline
How the Gregorian and Solar Hijri (Jalali) calendars line up: the ~621 year offset, the new-year gap, and a side-by-side table for recent years.
- Leap yearsسالهای کبیسه
What is a leap year? The 4 / 100 / 400 rule explained
A leap year has 366 days, with 29 February added to keep the calendar in sync with the Sun. Here is the 4/100/400 rule, why it exists, and a checker.
- Age & birthdaysسن و تولد
How old am I exactly? Age in years, months, and days
Your exact age in years, months, and days, not just the year count. Enter your birth date below, plus the method and why month lengths make it tricky.
- Calendar referenceمرجع تقویم
Persian (Jalali) calendar months in order, with meanings
The 12 Persian (Jalali / Shamsi) months in order, their lengths, Gregorian seasons, and what each name means, in a clean reference table you can bookmark.
- Calendar historyتاریخ تقویم
Why does February have 28 days (and sometimes 29)?
February is short because of Roman calendar politics, and it gains a 29th day on leap years. Here is the history and the rule, with a leap-year checker.
- Date mathحساب تاریخ
What day of the week was I born on?
Find the weekday you were born on in one tap. Pick your birth date below and get the answer, plus the simple math behind how weekdays repeat.
- Nowruzنوروز
How many days until Nowruz 2027?
Nowruz 2027 falls on Sunday, 21 March 2027. Here is the exact countdown, why the date lands on the 21st this year, and a live timer that ticks down.
- Date mathحساب تاریخ
How to calculate the number of days between two dates
Count the days between two dates by hand or with a calculator. The method, a worked example, the leap-year gotcha, and a live tool that does it instantly.
- Nowruzنوروز
Why Nowruz isn't always on the same Gregorian day
Nowruz tracks the spring equinox, so on the Gregorian calendar it lands on 20 or 21 March depending on the year. Here is why the date drifts, with a table.
- Leap yearsسالهای کبیسه
Persian (Jalali) leap years, explained
How leap years work in the Persian (Jalali / Solar Hijri) calendar, why the extra day is 30 Esfand, and the 33-year cycle behind the rule.