Tombstone Birthday Calculator by Ben Buckner revised by Danny Jones
Many older tombstones list age and date of death. This tool calculates birthdate from the
age of death and the date of death on the tombstone, death certificate or obituary.
Calculated dates should only be considered approximate due to possible errors or
possible different methodology used in the original calculation (found on the tombstone,
obituary or death certificate). Be sure to note in your records that your date was calculated.
This calculator can use either the exact month method or the 30 day month method to
compute a birthdate. While you may think the exact calendar month method may be more reliable,
be aware that many of the headstone and obituary ages at death appear to have been computed
using the 30-day-month method. (The 30-day-month method assumes that all months have 30 days.
It's an approximation which agrees with the exact calendar month method about 2/3 of the time.)
A tombstone or death certificate is not considered a primary source for a birthday, but it
can give you an approximate date of birth to help in further research.
The calculator could also be used to calculate birth year from census data or birthdate
from wedding date and age.
The calculator allows Julian calendar dates, but you cannot mix Julian and Gregorian
dates or ages in the same calculation.
Because of the change from the Julian to the Gregorian Calendar, the calculator may not
work for anyone born between Sept. 2, 1752 and Sept. 14, 1752 (or when days were lost at the