Jewish Calendar Accuracy Test
The Jewish calendar’s calculations attempt to follow the average length of the new moon. But the difference between the Jewish calendar’s average length of a new moon, and the actual length of the new moon is off by a very small amount.
The most accurate difference is -.57 seconds (Dr. Irv Bromberg, COGWA, Jewdaism 101). The approximate value of 3/5 of second is -.6 seconds (Approx. Dr. Irv Bromberg). 2 Millionths of a month is -.17 seconds (Avraham Yaakov Finkel). How much of a difference do any of these make in calculating the dates of the holy days using the Jewish calendar?
Jewish calendar calculations difference (in seconds)
Year range - BCE: ({{total_years}} years)
to
With a {{ (molad_diff > Math.floor(molad_diff)) ? molad_diff.toFixed(2):molad_diff }} second correction to the calculation of the Jewish calendar, {{errors_percentage}}% of the holy days from {{start_year}} to {{end_year}} ({{total_years}} years) are on the wrong date.
Earliest month:{{month_names[month_earliest]}}, Latest month: {{month_names[month_latest]}}
| Error (days diff.) |
Date (Jewish Molad) |
Date (corrected by {{molad_diff}} sec.) |
|---|---|---|
| {{date.days_diff}} * | {{date.tishri1_source_month}}/{{date.tishri1_source_day}}/{{date.gregorian_year}} | {{date.tishri1_month}}/{{date.tishri1_day}}/{{date.gregorian_year}} |
* This year has a difference between the inaccurate measurements of the average cycle of the new moon conjunction of the Jewish calendar compared to the corrected measurements.