Work out festival date estimate instantly with clear inputs, formula shown and shareable results.
Many festivals fall a fixed number of days from an astronomical or calendrical anchor, so the date is that anchor shifted by the offset, with the weekday derived from the result. Working from an anchor plus offset is exactly how movable feasts are defined, which is why the same offset gives a different calendar date each year.
Festival date
date = anchor date + offset in days
date = anchor date + offset in days. Many festivals fall a fixed number of days from an astronomical or calendrical anchor, so the date is that anchor shifted by the offset, with the weekday derived from the result.
Working from an anchor plus offset is exactly how movable feasts are defined, which is why the same offset gives a different calendar date each year.
Enter known anchor date, days after the anchor, count from. The defaults shown are a realistic worked example — swap in your own figures to get a result you can use.