Easy method to convert Jewish dates to Gregorian dates?

Question

Does anyone know of a method to make converting Jewish calendar dates to Gregorian calendar dates easy?

Also, is there a program or website that does this?

Answer 1

I use http://Hebcal.com for this.
N.B. I did some programming for them.

There is an algorithm that they use, but it's not simple enough to do by hand.

Answer 2

There are a number of sites that convert the calendar automatically such as hebcal.com and chabad.org (google is your friend). You can get the lisp conversion code from emacs.

The Calendar and the Diary

Emacs provides the functions of a desk calendar, with a diary of planned or past events.

p h Display Hebrew date for selected day (calendar-print-hebrew-date).

github-misc/Hebrew Calendar/code/cal-hebrew.el has the code used in 1209 lines of lisp.

You can see a summary article at Hebrew Dating which points to Calendrical Calculations: The Millennium Edition, Edward M. Reingold and Nachum
Dershowitz, Cambridge: Cambridge University Press, 2001. which gives the algorithms and calculations. There are also one page universal conversion sheets such as in

Calendrical Tabulations, 1900-2200, Edward M. Reingold and Nachum Dershowitz, Cambridge: Cambridge University Press, 2002. This book (see Fig. 1) gives a set of fully accurate, easy-to-use tabl es that simultaneously display the date on different calendars over a 300-year period.

Safari shows the lisp code used at Appendix B Lisp Implementation by Edward M. Reingold, Nachum Dershowitz

Answer 3

Probably not what you're looking for, but I feel compelled to point out that NodaTime, Jon Skeet's date/time .NET API, does conversions between calendars including Gregorian and Hebrew.