Historical Calendar Converter

Both dates refer to the same day number; no time elapses in the conversion. The Julian calendar adds a leap day every four years. Gregorian century years are leap years only when divisible by 400, so the date-label difference changes over time.

Historical adoption

The Gregorian reform began in 1582 in some countries; other countries adopted it later. Britain and its colonies switched in 1752, and Russia’s civil calendar in 1918. Religious and civil calendars may differ. This converter does not apply country-specific cutovers.