The ≈ marks dates for lunar-sighting or regionally-variable observances (Islamic, Hindu, Buddhist, and one Sikh date) that cannot be calculated with certainty years in advance. They are widely published estimates and may be confirmed a day earlier or later by local religious authorities closer to the date.
Christian dates that key off Easter, and Jewish Hebrew-calendar dates, follow fixed, well-documented arithmetic rules. They can be calculated exactly for any year with no lunar-sighting uncertainty, so they're shown as firm dates.
No — this covers the major, widely-recognized observances in six traditions. Minor or regional observances, and other traditions such as Baha'i or Jain calendars, aren't included yet.
The estimate-only dates are checked and refreshed roughly once a year as official confirmations come in. The computed dates never need updating — they're correct by definition for any year.
This calendar is a general planning reference, not a religious authority. For observance timing that matters for practice (e.g. exact prayer or fasting start times), always check with your local religious community.
