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| 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. | | 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. | ||
| Includes the calendar month method or the 30 day month method (8870 method) | | Includes the calendar month method (subtracts days first) or the 30 day month method (8870 method) | ||
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| [http://www.searchforancestors.com/utility/age.html Ancestor Search Age Calculator] | | [http://www.searchforancestors.com/utility/age.html Ancestor Search Age Calculator] | ||
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|[https://www.timeanddate.com/ Timeanddate.com] | |[https://www.timeanddate.com/ Timeanddate.com] | ||
| Calculates birthdate from age at death and age at death from birth and death date '''''[[Date Calculator|Instructions]]''''' | | Calculates birthdate from age at death and age at death from birth and death date '''''[[Date Calculator|Instructions]]''''' | ||
| Uses calendar month method | | Uses calendar month method. Shows results from subtracting years first AND shows results subtracting days first, if different. | ||
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| [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. | ||
| Has options to use calendar month method or 30 day month method (8870 method) | | Has options to use calendar month method (subtracts days first) or 30 day month method (8870 method) | ||
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== | ==Ways for Calculating Dates== | ||
There are | There are different ways to calculate a date from an age at death:<br> | ||
* | *Calendar month method | ||
*30 day month method (also known as 8870 method) | :*In addition, the calendar month method can be done two ways: | ||
::*Subtract days first, then months and years | |||
This can be explained with this example: | ::*Subtract years first, then months and days | ||
*Death date: | *30 day month method (also known as 8870 method)<br> | ||
*Age at death: | <br> | ||
* | ''This can be explained with this example:'' | ||
:* | *Death date: 1 Apr 1870 | ||
:*30 day month method: | *Age at death: 0 years 1 month, 4 days | ||
*Three answers can be given: | |||
:*Calendar month method: | |||
::*Subtract days first, then months and years: 28 Feb 1870 | |||
::*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? === | ===Which Method Should be Used? === | ||
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. | 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=== | ||
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*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>[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>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> | ||
*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> | ||
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