World Calendar Systems & Dates

The most widely used civil calendar worldwide, introduced by Pope Gregory XIII in 1582. Standard for international business and communication.

Introduced by Julius Caesar in 45 BCE, predecessor to the Gregorian calendar. Still used by some Orthodox churches for religious dates.

Official calendar of Iran and Afghanistan. One of the most accurate solar calendars, with year starting at Spring Equinox.

Used in Ethiopia and Eritrea, based on the Coptic calendar. Features 13 months - 12 months of 30 days plus a 5-6 day month.

Lunar calendar used to determine Islamic holidays like Ramadan and Eid. Began with Prophet Muhammad's migration to Medina in 622 CE.

Lunisolar calendar determining Jewish religious holidays. Adds leap months to stay aligned with seasons and agricultural cycle.

Ancient lunisolar calendar featuring 12-year zodiac cycle. Used for traditional festivals like Chinese New Year and Mid-Autumn Festival.

Used in Thailand, Cambodia, Laos, Myanmar. Year count begins with Buddha's death.

Traditional Hindu lunisolar calendar used across India and Nepal.

Based on imperial era system. Current era "Reiwa" began May 2019.

Official calendar of Thailand, based on Buddhist Era dating system.

Traditional Korean lunisolar calendar, similar to Chinese system.

Based on Chinese calendar with Vietnamese cultural adaptations.

Used by Jain community, begins with Lord Mahavira's nirvana.

Features 19 months of 19 days each, plus intercalary days.

Used by Coptic Orthodox Church, based on ancient Egyptian calendar.

Ancient Persian calendar used by Zoroastrian community.

Traditional calendar of Armenia, similar to ancient Egyptian system.

Ancient Mesoamerican calendar system with complex cyclical structure.

International standard date format (YYYY-MM-DD). Used in computing, data exchange, and international business.

Seconds since January 1, 1970 (UTC). Universal time representation in computer systems and programming.

Continuous count of days since 4713 BCE. Used in astronomy for precise astronomical calculations and observations.