Julian Date Converter
Ancient civil calendar
Ancient Egyptian Date Converter
Convert Gregorian dates to the ancient Egyptian civil calendar with twelve 30-day months and five epagomenal days.
Live output
Result
Choose a direction, enter a Gregorian or Egyptian civil date, and the fixed-calendar result appears here.
Guide
Ancient Egyptian Date Converter for civil calendar dates
This Ancient Egyptian Date Converter changes Gregorian dates into the fixed Egyptian civil calendar and converts Egyptian civil YYYY-MM-DD input back into Gregorian dates. The model uses twelve 30-day months followed by five epagomenal days.
The page is intentionally about the ancient civil calendar model. It does not apply later Alexandrian or Coptic leap-year rules, and it does not try to reconstruct local regnal dating or religious observance calendars.
What this converter handles
A fixed 365-day civil calendar model
The converter maps every date through a Julian Day Number reference. Egyptian civil years are counted as simple 365-day blocks, with month positions derived from the number of days since the configured epoch.
Month 13 is reserved for the five epagomenal days at the end of the civil year. Normal months have 30 days, so the validation rules are deliberately different from a Gregorian month/day field.
Gregorian to Egyptian civil
Enter a Gregorian date and return the Egyptian civil year, month, day, month label, and reference JDN.
Egyptian civil to Gregorian
Enter an Egyptian civil date as YYYY-MM-DD, using month 13 only for epagomenal days 01 through 05.
Seasonal month labels
The output includes familiar Greek-derived month labels such as Thoth, Athyr, and Mesore for easier comparison with references.
How to use it
Use month 13 only for epagomenal days
Choose Gregorian to Egyptian when your source is a standard Gregorian date. Choose Egyptian to Gregorian when your source is already written in this page's Egyptian civil numeric format.
Egyptian input must be YYYY-MM-DD. Months 01 through 12 accept days 01 through 30; month 13 accepts days 01 through 05 for the extra days at year end.
Convert from Gregorian
Enter a date such as 2026-06-30 to see the fixed Egyptian civil date and day-of-year position.
Convert from Egyptian civil
Enter a value such as 2775-03-15. Use 2775-13-01 through 2775-13-05 for epagomenal examples.
Watch for later calendar systems
Do not use this page for Alexandrian, Coptic, or modern Egyptian civil dates because those use different rules.
Reference examples
Reference conversions from the local implementation
These examples are generated by the same fixed-year functions used by the live form. They show how the converter reports both the numeric date and the readable month label.
Gregorian to Egyptian civil
The Gregorian date 2026-06-30 converts to Egyptian civil 2775-03-15, shown as Athyr 15, Year 2775, with reference JDN 2461222.
Egyptian civil to Gregorian
The Egyptian civil date 2775-03-15 converts back to Gregorian 2026-06-30 in this fixed 365-day model.
FAQ
Ancient Egyptian conversion questions
The main risk with Egyptian calendar conversion is mixing related but different calendar systems. These answers define the exact model used here.
Does this converter include leap years?
No. It uses the ancient Egyptian civil model with 365 days every year. Later leap-year reforms are outside this page.
Why is there a month 13?
Month 13 represents the five epagomenal days after the twelve 30-day months. It is valid only for days 01 through 05.
Is this the same as the Coptic calendar?
No. The Coptic calendar has its own era and leap-year behavior. Use the separate Coptic Date Converter for Coptic dates.
Reference
Calendar implementation reference
The implementation follows the standard absolute-day arithmetic approach used for fixed historical calendars: count days from an epoch, divide into calendar years and months, and convert back through the same day count.