Birth and Death Date Calculators: Difference between revisions

From FamilySearch Wiki
VisualWikitext
No edit summary
(27 intermediate revisions by 2 users not shown)
Line 9: Line 9:
|[http://freepages.rootsweb.com/~fgris/family/brown/agecalc.html Age Calculator]  
|[http://freepages.rootsweb.com/~fgris/family/brown/agecalc.html Age Calculator]  
|Rootsweb  
|Rootsweb  
| Used to calculate birthdate using date of death and age; calculate age of death with birthdate and death date; calculate death with only the year of birth and death. 
| Has 4 various calculators to determine birth date and age including the '''**8870''' method
| Includes the calendar month method (subtracts days first) or the 30 day month method (8870 method)
| Uses exact month method
|-
|-
| [http://www.searchforancestors.com/utility/age.html  Ancestor Search Age Calculator]  
| [http://www.searchforancestors.com/utility/age.html  Ancestor Search Age Calculator]  
| [http://www.searchforancestors.com/ searchforancestors.com]  
| [http://www.searchforancestors.com/ searchforancestors.com]  
| Used to determine age from birth date and death date
| Used to determine exact age from birth date and death date
|  
| Uses exact month method
|-
|[https://www.timeanddate.com/date/dateadded.html Date Calculator]
|[https://www.timeanddate.com/ Timeanddate.com] '''''[[Date Calculator|Instructions]]'''''
| Calculates birthdate from age at death and age at death from birth and death date
| Uses 30 day month method
|-
|-
| [http://longislandgenealogy.com/birth.html Birth Date Calculator]  
| [http://longislandgenealogy.com/birth.html Birth Date Calculator]  
| [http://longislandgenealogy.com longislandgenealogy.com]  
| [http://longislandgenealogy.com longislandgenealogy.com]  
| Used to determine birthdate from age at death
| Used to determine birthdate from age at death
| Uses 30 day month method (8870 method)
| Use exact month method
|-
|[https://www.timeanddate.com/date/dateadded.html Date Calculator]
|[https://www.timeanddate.com/ Timeanddate.com]
| Calculates birthdate from age at death and age at death from birth and death date  '''''[[Date Calculator|Instructions]]'''''
| Uses calendar month method. Shows results from subtracting years first AND shows results subtracting days first, if different.
|-
|-
| [http://www.searchforancestors.com/utility/birthday.html Tombstone Birthday Calculator]  
| [http://www.searchforancestors.com/utility/birthday.html Tombstone Birthday Calculator]  
| [http://www.searchforancestors.com/ searchforancestors.com]  
| [http://www.searchforancestors.com/ searchforancestors.com]  
| This calculator allows Julian calendar '''or''' Gregorian dates to help you calculate birth date from age at date of death.  
| This calculator allows Julian calendar '''or''' Gregorian dates to help you calculate birth date from age at date of death. This calendar also allows for an exact month or 30 day month method
| Has options to use calendar month method (subtracts days first) or 30 day month method (8870 method)
| Has options to use exact month or 30 day method
|}
|}


==Calculating Birth Dates==  
==Calculating Birth Dates==  


Sometimes a birthdate is not know and the date of death with the age listed in Years-months-days is provided. This requires a calculator to be used to determine the birthdate. There are several different kinds of calculators to use in determining a person's birth or death date. The method used by the calculator will give you different results.  
We all know that having birth dates helps us to complete the information for our ancestors and birth dates many times are much harder to find the further back you go. But many times we at least have the date of death with the age listed in Years-months-days.  


Age of death can be found in:
This information can be found on
{|  
{|  
|-
|-
Line 44: Line 44:
*old cemetery stones
*old cemetery stones
|
|
*church records
*church record
*some obituaries
*possibly Obituaries
|}
|}


==Ways for Calculating Dates==
==Calculating Dates Using Online Calculators==
There are different ways to calculate a date from an age at death:<br>
There are two ways to calculate a date from an age at death:<br>
*Calendar month method
*30 day month method; example: 28 Apr 1864
:*In addition, the calendar month method can be done two ways:
*exact month method; example: 30 Apr 1864
::*Subtract days first, then months and years
 
::*Subtract years first, then months and days
This can be explained with this example:  
*30 day month method (also known as 8870 method)<br>
Death date: 13 Mar 1870
<br>
Age at death: 5 years 10 months, 13 days,
''This can be explained with this example:''
Two answers can be given:
*Death date: 1 Apr 1870
Exact month method: 30 Apr 1864
*Age at death: 0 years 1 month, 4 days  
30 day month method: 28 Apr 1864
*Three answers can be given:
 
:*Calendar month method:  
===Which Way is Better?===
::*Subtract days first, then months and years: 28 Feb 1870
That just depends on how you wish to calculate the date. The 30 day month method assumes that all months have 30 days, whereas the exact month method uses the exact amount of dyas for each month.<br>
::*Subtract years first, then months and days: 25 Feb 1870
:*30 day month method: 27 Feb 1870 (matches 8870 method)


===Which Method Should be Used? ===
Although, the exact month method would be more accurate when calculating a date. Some believe that the dates and ages calculated and found on tombstones uses the 30 day month method.<ref> searchforancestors.com ''Tombstone Birthday Calculator'', http://www.searchforancestors.com/utility/birthday.html,  accessed 25 June 2021. Quote: "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.)"</ref>
Although, the calendar month method may take into account the correct number days of the month, it is a common belief that the 30-day-month method or the '''8870''' hand method used for years before calculators is the method most often used. <ref> searchforancestors.com ''Tombstone Birthday Calculator'', http://www.searchforancestors.com/utility/birthday.html,  accessed 25 June 2021. Quote: "While you may think the 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 calendar month method about 2/3 of the time.)"</ref> This 30 day month method would have been the easiest way for the individual to calculate the date for the tombstone inscription.


===Tips===
===Tips===
Line 74: Line 71:
*Calculators can be used to approximate a birth year from:  1) census data  2) birth date from wedding date and age.
*Calculators can be used to approximate a birth year from:  1) census data  2) birth date from wedding date and age.
*Use either the Julian or Gregorian Calendar. Do not used the two together.
*Use either the Julian or Gregorian Calendar. Do not used the two together.
*There is what is called a 30-day-month/or '''**8870''' method which assumes that all months have 30 days. As searchancestors.com says: "...many of the headstones and obituary ages at death appear to have been computed using this method. It's an approximation which agrees with the exact calendar month method about 2/3 of the time.)"<ref>Amy Larner Giroux, ''Skillbuilding: Date Calculations'' https://bcgcertification.org/skillbuilding-date-calculations/ accessed 30 June 2021;[http://www.searchforancestors.com/utility/birthday.html Ancestor search]</ref>
*There is what is called a 30-day-month/or '''**8870''' method which assumes that all months have 30 days. As searchancestors.com says: "...many of the headstones and obituary ages at death appear to have been computed using this method. It's an approximation which agrees with the exact calendar month method about 2/3 of the time.)"<ref>[http://www.searchforancestors.com/utility/birthday.html Ancestor search]</ref>
*searchforancestors.com: "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."<ref>[http://www.searchforancestors.com/utility/birthday.html Ancestor search]</ref>
*searchforancestors.com: "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."<ref>[http://www.searchforancestors.com/utility/birthday.html Ancestor search]</ref>
*The calendar was changed from the Julian to Gregorian calendar at some point in a country's history. Each country had a different date. Be sure to do the calculation with the correct calendar. Use this resource: [http://www.searchforancestors.com/utility/gregorian.html change from Julian to Gregorian calendar Dates by country].<ref>[http://www.searchforancestors.com/utility/birthday.html Ancestor search]</ref>
*The calendar was changed from the Julian to Gregorian calendar at some point in a country's history. Each country had a different date. Be sure to do the calculation with the correct calendar. Use this resource: [http://www.searchforancestors.com/utility/gregorian.html change from Julian to Gregorian calendar Dates by country].<ref>[http://www.searchforancestors.com/utility/birthday.html Ancestor search]</ref>

Revision as of 13:45, 25 June 2021

Online Birth and Death Date Calculators[edit | edit source]

Links Website Description Method
Age Calculator Rootsweb Has 4 various calculators to determine birth date and age including the **8870 method Uses exact month method
Ancestor Search Age Calculator searchforancestors.com Used to determine exact age from birth date and death date Uses exact month method
Date Calculator Timeanddate.com Instructions Calculates birthdate from age at death and age at death from birth and death date Uses 30 day month method
Birth Date Calculator longislandgenealogy.com Used to determine birthdate from age at death Use exact month method
Tombstone Birthday Calculator searchforancestors.com This calculator allows Julian calendar or Gregorian dates to help you calculate birth date from age at date of death. This calendar also allows for an exact month or 30 day month method Has options to use exact month or 30 day method

Calculating Birth Dates[edit | edit source]

We all know that having birth dates helps us to complete the information for our ancestors and birth dates many times are much harder to find the further back you go. But many times we at least have the date of death with the age listed in Years-months-days.

This information can be found on

  • death records
  • old cemetery stones
  • church record
  • possibly Obituaries

Calculating Dates Using Online Calculators[edit | edit source]

There are two ways to calculate a date from an age at death:

  • 30 day month method; example: 28 Apr 1864
  • exact month method; example: 30 Apr 1864

This can be explained with this example: Death date: 13 Mar 1870 Age at death: 5 years 10 months, 13 days, Two answers can be given: Exact month method: 30 Apr 1864 30 day month method: 28 Apr 1864

Which Way is Better?[edit | edit source]

That just depends on how you wish to calculate the date. The 30 day month method assumes that all months have 30 days, whereas the exact month method uses the exact amount of dyas for each month.

Although, the exact month method would be more accurate when calculating a date. Some believe that the dates and ages calculated and found on tombstones uses the 30 day month method.[1]

Tips[edit | edit source]

  • Be aware that some of these websites have other types of calculators with different functions, explanations and tips, with various kinds of information.
  • Some calculators may require you to put a 0 in a box instead of leaving a box blank, also using a 0 in front of a single digit month may or may not be required.
  • Due to possible errors or different methodology used in Calculated dates from original calculations. (found on the tombstone, obituary or death certificates) , please make a note in your records that the date was calculated..
  • Calculators can be used to approximate a birth year from: 1) census data 2) birth date from wedding date and age.
  • Use either the Julian or Gregorian Calendar. Do not used the two together.
  • There is what is called a 30-day-month/or **8870 method which assumes that all months have 30 days. As searchancestors.com says: "...many of the headstones and obituary ages at death appear to have been computed using this method. It's an approximation which agrees with the exact calendar month method about 2/3 of the time.)"[2]
  • searchforancestors.com: "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."[3]
  • The calendar was changed from the Julian to Gregorian calendar at some point in a country's history. Each country had a different date. Be sure to do the calculation with the correct calendar. Use this resource: change from Julian to Gregorian calendar Dates by country.[4]

How to calculate by hand - Estimated date[edit | edit source]

There is what is called a 30-day-month/or **8870 method which assumes that all months have 30 days, many of the headstones and obituary ages at death appear to have been computed using this method. It's an approximation which agrees with the exact calendar month method about 2/3 of the time.

When the online calculator is not available, use the **8870 formula or the 30 day month length [5]

For example: 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 

   -Subtract constant 8870

________ 18170927 Born 27 Sept. 1817 (yyyymmdd) 1817yr-09mo-27dd

This person was born on September 27, 1817

References[edit | edit source]

  1. ↑ searchforancestors.com Tombstone Birthday Calculator, http://www.searchforancestors.com/utility/birthday.html, accessed 25 June 2021. Quote: "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.)"
  2. ↑ Ancestor search
  3. ↑ Ancestor search
  4. ↑ Ancestor search
  5. ↑ Search for ancestors
Retrieved from "https://integration-ru.familysearch.org/en/wiki/index.php?title=Birth_and_Death_Date_Calculators&oldid=4497008"