I actually tested TMG's date calculator with a few samples against my own calculations subtracting (or adding) years then months then days. I found that it did take into consideration 30 vs 31 day months, why wouldn't it as they are a know entity. So when counting days into a partial month, it will use 30 or 31 days for the preceding month as appropriate. However, it does not cater for leap years when the preceding month is February, but always uses 28 days. So if your calculation of the number of days goes into March it would be correct unless it was a leap year when it would be 1 day more than it should be. Of course, this does not help us to know exactly how our ancestors calculated these Year, Month and Day times! As for using Microsoft products to calculate dates be aware that Excel thinks 1900 was a leap year unless you use an add-in to correct that. I can't comment on other their products as I haven't used them for date calculations. Graeme Simpson >Thank you, John, Rick, and Lee for explaining the proper way of >calculating the putative date of birth. On stones I've seen with birth >and death dates plus years-months-days, it worked correctly whether >working forward (from the date of birth) or backward (from the date of >death). > >Lee, you solved the puzzle for me--every month is 30 days--so that, >ok, 22 Feb to 22 Mar is one month; then 9 days left in March to day of >death, 15 Apr, boom, that's 24. So, it works correctly working forward >as well as backward. That's what puzzled me when I wondered about Feb. >plus a leap year because when someone dies, one starts with the >deceased's age at the last birthday and works forward to the day of >death and it makes sense to ignore the actual number of days in each >month. I was overthinking it after all. > >Thanks again to each of you. > > Sam