What is the Ancient Egyptian Civil Calendar?

One of the earliest well-documented civil calendars. The civil year was divided into three seasons—Akhet, Peret, and Shemu—with four months in each season. Because the classic civil form had no leap day, it drifted through the seasons over long periods.

How the calendar is structured

12 months of 30 days plus 5 epagomenal days; 365-day civil year.

Where and why it is used

Region: Ancient Egypt. Primary context: Historical study, Egyptology, chronology.

History and development

The system belongs to the Ancient layer of the archive. Its origin is summarized as At least Old Kingdom era. CalculatorWiser separates historical reconstruction, religious observance, civil use, and modern technical standards so different systems are not treated as though they all work the same way.

Visual reference gallery

Conversion and accuracy notes

Some calendar systems can be converted deterministically with modern algorithms. Others depend on observation, local authority, historical reconstruction, or regional practice. CalculatorWiser marks those distinctions rather than presenting uncertain dates as exact.

Research trail

This entry is part of the research-backed World Calendar Archive. Primary research anchor for this entry: The Metropolitan Museum of Art.