User:LeeA/sandbox/testing4

Calculating Birth Dates
Having exact birth and death dates for our ancestors helps us confirm our finds, as well as better identify them in other records. However, finding precise dates can be much more difficult as we research further back in time. We may only have our ancestor’s age (sometimes in the format of years/months/days) at time of death. Or, we may wish to know how old an ancestor would be from their birth date. Using a date calculator can help us with the addition and subtraction necessary to discover our a more precise date.

This information can be found on

Using a Date Calculator
Like the one below can help you determine the following information.


 * To determine a date of Birth from a Death date: Put in the known Death date click Subtract then the age given in years/months/weeks/days then click the calculate button.  The answer is under the lower left corner under the colored box.


 * To determine a date of Death from a Birth date: Put in the Known Birth date click Add then put in the age given in years/months/weeks/days and click calculate.


 * To determine an age: use the Duration Between Two Dates calculator listed below the "live" calculator, putting in the beginning date and the ending date, then click calculate.

The Following is an example of a Date Calculator that is on the Date and Time web page, click on the picture or on the link that is just below the picture to go to a live calculator, have fun doing your own calculating of Dates. (other online calculator websites listed below)



On line Date calculator Date Calculator website

Tips

 * Due to possible errors or different methodology used in Calculated dates (found on the tombstone, obituary or death certificates) from original calculations, please note in your records that the date was calculated..


 * The calculator could also be used to calculate birth year from census data or birth date from wedding date and age.


 * 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.)


 * 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.


 * Be aware the calendar was changed from Julian to Gregorian in which ever country for which you are performing the calculation. See the change from Julian to Gregorian calendar Dates by country.

How to calculate by hand
When the online calculator is not available, use the 8870 formula.(the calculator calls this the 30 day month length)

If a person died May 6, 1889 at age 71 years, 7 months and 9 days:

18890506 Year, day, month of death (yyyymmdd) 1889--05---06 -710709 Subtract age at death (yymmdd) _________  - 71yr-07mo-09dd 18179797   -8870 Subtract constant 8870 ________ 18170927 Born 27 Sept. 1817 (yyyymmdd) 1817yr-09mo-27dd

This person was born on September 27, 1817