Provided by Jerry Merritt of the West Florida Genealogical Society (WFGS)
Calculate Birthdate from Tombstone Death Data
Often, tombstones will list only a date of death and an age at death in days, months and years.
This calculator will give you the date of birth if you enter the date of death and age.
While the calculator will give you an accurate date of birth based on the date of death and age, don’t be misled into thinking that the calculated correct answer is the actual date of birth. Stone carvers used several indirect methods to calculate the age from date of birth and many of these methods – such as the Rule of 8870 – sometimes gave dates slightly different from the actual birth date.