Convert any Gregorian date to the Islamic (Hijri), Hebrew, Persian (Jalali), and Julian calendars.
| Hijri (Islamic) | Tabular (arithmetic) calendar. The religious calendar follows moon sighting, so observed dates can differ by 1–2 days. |
| Hebrew (Jewish) | The fixed arithmetic calendar with the traditional postponement rules. |
| Persian (Jalali) | Solar Hijri, astronomically anchored (equinox-based). |
| Julian | The proleptic Julian calendar — the date under the old system. |