Calendar Tools & Converters
Convert any date between the world's calendar systems — Islamic, Hebrew, Persian, Indian, Julian and more — plus the retail 4-5-4 calendar and a leap-year checker. Every conversion uses the authoritative calendar data built into your browser, computed on your device and never uploaded.
- Calendar Converter One date, every calendar: see today (or any date) in the Hijri, Hebrew, Persian, Indian, Buddhist, Julian and more
- Hijri (Islamic) Date Converter Gregorian ↔ Hijri in both directions
- Persian (Solar Hijri) Calendar Converter Gregorian ↔ Persian (Jalali) in both directions
- Julian Calendar & Julian Day Converter Julian ↔ Gregorian for historical dates, plus the astronomical Julian Day Number
- Nepali Date Converter (BS ⇄ AD) Bikram Sambat ⇄ Gregorian, both ways
- Hebrew Calendar Converter See any Gregorian date in the Hebrew calendar
- 4-5-4 Retail Calendar What retail week is today? Map any date to its NRF 4-5-4 fiscal year, quarter, month and week
- Leap Year Calculator Is it a leap year? Get a yes/no for any year with the rule explained
How the world keeps time
The Gregorian calendar is only one of many. The Hijri (Islamic) calendar is lunar and drifts against the seasons; the Hebrew calendar is lunisolar with leap months; the Persian (Solar Hijri) calendar is astronomically precise; and the Julian calendar still sets some religious dates. These converters translate a date between them using each system's own algorithm, so you can line up a birthday, holiday or historical event across calendars.
All conversions are computed in your browser from the calendrical rules — no lookup service, no upload — and work offline. For timestamps, time zones and everyday date math, see Date & Time.
Frequently asked questions
How can these calendar conversions be accurate without a server?
Modern browsers ship the full ICU/CLDR calendar database — the same data operating systems use — covering the Islamic, Hebrew, Persian, Indian, Buddhist, Japanese, Chinese and other calendars. These tools read that data directly, so conversions are authoritative and run entirely on your device, even offline.
Which calendar systems are covered?
Gregorian, Islamic (Hijri, both Umm al-Qura and tabular), Persian (Solar Hijri/Jalali), Hebrew, Indian National (Saka), Buddhist, Coptic, Ethiopian, Minguo (ROC), Japanese era, Chinese, the Julian calendar and Julian Day Numbers — plus the NRF 4-5-4 retail calendar and a leap-year checker.
Are religious dates like Ramadan exact?
The tools give the civil (calculated) date — for Islam, the Umm al-Qura calendar. Religious observances are often fixed by moon sighting and can differ by a day and by country, so treat the civil date as a close reference, not a ruling.