Amidora · Library
How can the same instant belong to different civil dates in two time zones?
At 22:30 UTC on 2024-10-02 it is already 2024-10-03 in Jerusalem: that is 1 Tishrei 5785 there, but 29 Elul 5784 for the same instant read as a UTC or New York date.
What the converter actually receives
The converter accepts a civil date, not a moment. It builds that date at noon UTC and formats it in the Hebrew calendar, so the result depends only on which calendar day you typed. Turning a timestamp into that day is a separate step, and it depends on the time zone you display it in.
Neither step looks at sunset. The Hebrew day boundary at local sunset is a third question that a date-only converter cannot answer.
From timestamp to Hebrew date
- Write down the timestamp with its offset, or the local time and place.
- Decide which time zone defines the civil date you need.
- Convert the timestamp to a civil date in that zone.
- Enter that civil date in the converter and record the zone next to the result.
- Keep the place and whether the event was before or after sunset separately, if that matters.
One instant, two Hebrew years
The instant 2024-10-02 22:30 UTC is 2024-10-03 01:30 in Jerusalem and 2024-10-02 18:30 in New York. Entered as a civil date, 2024-10-02 converts to 29 Elul 5784 and 2024-10-03 to 1 Tishrei 5785, so the same moment falls in different Hebrew years depending on the zone used. A second instant, 2024-03-01 03:30 UTC, is still 2024-02-29 19:30 in Los Angeles: 20 Adar I 5784 there, 21 Adar I 5784 by the UTC date.
- Jerusalem date
- 2024-10-03 · 1 Tishrei 5785
- New York or UTC date
- 2024-10-02 · 29 Elul 5784
- Los Angeles date
- 2024-02-29 · 20 Adar I 5784
- UTC date
- 2024-03-01 · 21 Adar I 5784
Mistakes
- Taking the date part of a UTC timestamp as the local civil date.
- Assuming the converter applies the time zone of your device.
- Confusing a time-zone date change with the sunset boundary.
- Saving a converted Hebrew date without the zone used to get it.
Limits
ECMA-402 DateTimeFormat, listed below, defines how a time zone turns an instant into a date, and the Hebcal documentation describes the conversion. The converter adds no sunset or observance calculation.