Hi, My genealogy software (Family Origins 8.0) calculates Jesse's birthdate as September 17, 1784 and Lucinda's birthdate as April 19, 1789. Lucinda's is too far off, exactly one year, to be due to an leap year calculation error. I doubt if Jesse's is in error either. Christening date & birth date may be a difference. To answer your question on where to to find a caluclator. Go to the following site if your genealogy software doesn't make the calculation: http://enws347.eas.asu.edu:8000/~buckner/bdform.html Jesse's birthdate is calculated as September 17 or 18 by this site according to real month or 30 day month. This site is located on Cyndi's List which has multiple sites on calenders & dates. See the following: http://www.cyndislist.com/calendar.htm My mother died in 1990 in Hancock County. She always said her birthday was something else than what her birth certificate indicated. Therefore her tombstone has her version of her birthday although her birth certificate has been proven to be correct. Her tombstone is now incorrect by 4 days. Chet in Champaign