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-- Age Calculator --

This calculator will do four different calculations regarding age. It has two methods of calculating a birthdate, given the date of death and age at death. The first one is more accurate, but the second one, called the 8870 method, which assumes 30-day months, is sometimes better since the age-at-death inscribed on headstones often seems to have been figured on the basis of 30-day months. So if the first one gives you a birthdate like Feb. 31, try the second.

Calculate birthdate, using age at death and date of death

Calculate birthdate, using age at death and date of death, with the 8870 method

Calculate age at death, using birthdate and date of death

Calculate approximate age at death, using only year of birth and year of death

Age at death: Years Months Days

Birthdate: Month Day Year

Date of death: Month Day Year


Type in a date and this will return the day of the week. Like the calculator above, it should work for anything after Sept. 14, 1752, when the calendar changed from Julian to Gregorian.
Day Month Year


The algorithm I use for the 8870 method was taken from the website of the Board for Certification of Genealogists. It goes: The result will be the date of birth in YYYYMMDD format.