One converter for every calendar you'll meet
Birth certificates, court papers, astronomy logs, religious holidays and old manuscripts are rarely written in the calendar you use day to day. This tool takes a single date in Shamsi, Islamic, Gregorian, the Julian calendar or a bare Julian Day Number and returns all of them at once, so you never have to guess how Farvardin 1 maps to March, or which Gregorian night Ramadan begins. Every value updates as you type and is computed locally in your browser.
Why four systems, and what a Julian Day Number is
The Gregorian (Miladi) calendar is the global civil standard. The Persian or Shamsi calendar is solar and begins at the spring equinox — its New Year, Nowruz, falls on 21 March. The Islamic or Hijri calendar is lunar, about 10–12 days shorter each year, so its months drift through the seasons. The Julian Day Number (JDN) is a running count of days astronomers use; we anchor every date to a JDN so all four systems always agree exactly. The Julian calendar predates the Gregorian reform and is still used in some liturgical contexts.
Date math and differences that respect each calendar
Switch to Add / Subtract to find a future or past date — '90 days after' or '3 Persian months before' — and read the result in all systems at once. The Difference tab counts the exact days between any two dates (each typed in its own calendar) and then expresses that span as years, months and days within Gregorian, Shamsi, Islamic and Julian alike, which is ideal for ages, tenures, contract lengths and historical gaps.
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- 4-way instant conversion: Shamsi ⇄ Islamic ⇄ Gregorian ⇄ Julian Day Number
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- Julian civil calendar date and weekday for every instant
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- ‘Today across calendars’ strip — the current date in all five systems at a glance
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- Day details: weekday, day-of-year, ISO week, days-from-today & Unix timestamp
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- Add or subtract days, weeks, months & years across all calendars
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- Day-difference calculator with a years/months/days breakdown per calendar
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- Persian & Islamic month names with transliteration plus leap-year (kabiseh) flags
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- One-click copy per calendar, ‘Copy all’ and a ‘Today’ shortcut — runs fully in your browser
