I thot I would share with you my reply to a subject on another List concerning the calculation of birth dates. I would like to know from the List what your practices are? The discussion arose when someone offered a simple formula to back- calculate the date of birth based upon the age in years, months and days at the time of death. That formula can best be described as the 8870 method. A gentleman named Coy sent a URL on the subject, for which see. http://enws347.eas.asu.edu:8000/~buckner/bdform.html If you visit the web site, and read the explanation about the use of dates in times past, you should then have an appreciation for the inexactitude (by current standards) of the use of dates before say, 1880. In a nutshell, it would only add to erroneous date notation to calculate back to an exact date of someone's birth from a statement of their age at the time of their death. I checked the coding used by the owner of the URL, and it is my belief that none of his algorithims will consistently yield an exact, repeat exact, calender date by today's standards either. There is a website which offers a calender "picture" back to earlier times. It too has made certain, untrue assumptions based upon modern practices of uneven days to the month in order to account for a 365 and 1/4 day year. I don't have the URL to that site. I wrote the owner, and he never replied, so I discarded the address. I wondered why my "date calculator" in my genealogy program often yielded an incorrect year. My genealogy program offers no explanation of the algorithm used for calculating dates, and apparently there are many, starting with the simplistic "8870" device and others assuming a standard 28-day month and another a 30-day month. Anyway, by luck, I decided early on to cite only the year, qualified by an "ABOUT" plus a statement for the basis of the estimate, in my genealogy, when figuring out the birthdate from year/month/day notation on records and gravestones. Even if I'm off a year in an extreme case, my error rate will be less than having cited birth dates to the day (which would imply an unwarranted precision, so it seems.) Some authors in print, without explanation, cite just the year of birth, in instances when the age at death is known. Others simply leave the birth date out. I thought it was to save printing expense. I understand better now. I also now understand why the date of "30 February, 18xx" was written in one genealogy, and why in some instances the expression "last day of (month here), (year here)" was used. In my opinion, the best that can be done with written dates is to let them stand as they are, not convert them from "Old Style" to "New Style", or from "Quaker" to "Regular", or by any other technique. 'Gene Hubbard