Intended for death dates after 1752
Information revised from The ASSOCIATION FOR GRAVESTONE STUDIES, Greenfield, MA

 

Capt. John Goodwin’s gravestone says he died on May 25, 1842 at the age of 36 years, 2 months, 10 days.

To figure his birth date:
                                                                                  YRS        MOS         DAYS
Write death date on one line                                 1842           5               25
Subtract the year, month and day of age             -    36            2               10
                                                                                 ________________________
Birth date                                                               1806           3               15
RESULT:  Born March 15, 1806

 

If his age had been 60 years, 8 months and 5 days, to figure his birth date:

                                                                                  YRS                        MOS         DAYS     
It is necessary to borrow 12 months             Death 1842-1yr= 1841    5+12= 17       25
from the year to provide a figure                  Age                           60                  8          5
from which the months of his age can                    -  ______________________________
be deducted.                                             Birth date                1781                  9         20
                                                                              RESULT:  Born September 20, 1781

 

If his age had been 45 years, 8 months, 28 days, to figure his birth date:
                                                             
                                                                                   YRS                      MOS          DAYS
Both months and days must be        Death 1842-1yr= 1841     5-1=4+12= 16     25+30=55
taken from the years and months      Age                         45                          8                  28
to provide for deductions.  The                        -  _________________________________
adjustments required to provide       Birth date          1796                          8                27
for deductions must be taken as                            RESULT:  Born August 27, 1796
30 days when “borrowing” from
the month’s figure and as 12 months
from the year figure.  Calculate the
days first, months second, and year
last to avoid error.

 

 

NOTE: Britain (including the colonies and Canada) did not adapt the Gregorian calendar until 1752 when September 3 was made September 14.  This calculation for dates prior to that will be in error.