Question 1

How were ages recorded in historical records?

Accepted Answer

Ages may be recorded with varying levels of precision. Some records give age in years, months, and days: “aged 71 years, 5 months and 9 days.” Others use an ordinal year, such as “in the 71st year of his age.” Civil records more commonly give age in completed years alone, such as “71 years.”

Question 2

What is an ordinal year?

Accepted Answer

An ordinal year describes the year of life a person is currently in, rather than the number of years they have completed. “In the 71st year of his age” means the person had completed 70 years and was between their seventieth and seventy-first birthdays. Entering it as 71 would place the birth a year too early. The same idea applies to an infant: a child is “in the 1st year of their age” until they reach their first birthday.

Question 3

How is an age in completed years calculated?

Accepted Answer

An age in years alone, with no months or days, is the most common form in civil records and the least precise. A person recorded as 71 years old could have been born within a known window of time, and the result is shown as that window rather than a single date. Where a month is included, the possible birth date range narrows; where days are included, the birth date can be calculated to the day.

Question 4

How do I calculate a birth date from a tombstone?

Accepted Answer

The Birth Date calculator works like a tombstone calculator. It uses the death date and age recorded on a gravestone to calculate the person’s birth date. Enter the death date from the gravestone and the age at death in years, months, and days. The calculator works backward to the birth date, showing a range when the months or days are not known.

Question 5

What if I do not have a complete death date?

Accepted Answer

A birth date range can still be calculated when the death date is incomplete. If only the year, or the month and year, is known, the calculator carries that uncertainty through to the result and shows a range rather than filling in a specific date.

Question 6

What if the recorded age is approximate?

Accepted Answer

If a record gives an approximate age, such as “about 60 years,” enter the age as recorded. The calculator works from the age entered, so the date it gives is only as exact as that estimated age will allow.

Question 7

Why doesn’t the calculator use the 8870 shortcut?

Accepted Answer

A traditional method for tombstone dates writes the death date as an eight-digit number, subtracts the age written the same way, and subtracts a further 8870 to correct for the month lengths the method has assumed. It is quick to do by hand and usually lands within a day or two of the true date. The error comes from treating every month as thirty days. This calculator subtracts years, months, and days against the actual calendar, so the month lengths are the real ones and February is the length it was in that year, accounting for leap years. Where a date is given only as a year, or as a month and year, the missing precision is carried through as a range instead of being filled in with a guess.

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