How is the date of Holy Week calculated each year?

Annual Holy Week calendar: why does the date vary?

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Published in 03-15-2025

Easter Week is a Christian celebration that commemorates the passion, death, and resurrection of Jesus Christ. Unlike other fixed-date holidays, Easter Week changes each year due to its relationship with the lunar calendar.

How the date of Easter Week is determined:
The date of Easter Week is based on the Christian liturgical calendar, specifically Easter Sunday. According to the Council of Nicaea in 325 A.D., it was determined that Easter would be celebrated on the first Sunday after the first full moon following the spring equinox. This means that Easter can occur between March 22 and April 25.

Holy week date variation and it's history, connection between the equinox, the moon, and tradition

Why the date changes each year:
The change in the date of Easter Week is due to the liturgical calendar following the lunar cycle rather than the solar calendar used in daily life. Since the full moon varies each year, the date of Easter also changes, affecting the rest of Easter Week.

Relationship with the lunar calendar:
The determination of Easter is linked to the ecclesiastical full moon, which does not always coincide with the astronomical full moon. This is because the Church uses calculations based on the ecclesiastical calendar rather than exact astronomical observations.

Key days of Easter Week:
Palm Sunday: Marks the beginning of Easter Week with the commemoration of Jesus' triumphant entry into Jerusalem.
Holy Thursday: Commemorates the Last Supper of Jesus with his disciples and the institution of the Eucharist.
Good Friday: The day that remembers the crucifixion and death of Jesus.
Holy Saturday: A day of reflection in anticipation of the resurrection.
Easter Sunday: Celebration of Jesus' triumph over death and the most important day in Christianity.

The variability in the date of Easter Week makes this celebration a dynamic event that depends on astronomical and ecclesiastical factors. Understanding how it is calculated helps to comprehend its significance within the Christian calendar and its impact on different cultures and traditions worldwide.