Tombstone Birthday Calculator by Ben Buckner
revised by Danny Jones

Many older tombstones only 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).

CALENDAR:  Gregorian Julian
MONTH LENGTH:  Calendar months 30-day

Enter the person's date of death - Month Day, Year
DEATH DATE: Month  DD  YYYY  January February March April May June July August September October November December  ,

Enter the person's age at death - Years Months Days
AGE AT DEATH: YYY  MM  DD 

Click to CALCULATE BIRTHDATE:    

CALCULATED BIRTH DATE:  ,

• 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 calendar changeover.