Age At Death Calculator

Enter a birth date and a death date to get the age in years, months and days, even when the day or month is missing. Or enter a date and an age to get the birth year.

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The Age At Death Calculator works out how old someone was when they died, or how old they were on any record date. Enter a date of birth and a date of death and you get the age in years, months and days, plus the total number of days. If the day or the month is unknown, as it often is in old records, the answer becomes a range with a minimum and a maximum age. A second tab goes the other way: enter a date and the age given for that date, for example “aged 34” in a census or on a gravestone, and it shows the earliest and latest possible birth date and the birth year or years. Everything is calculated in your browser and nothing is sent anywhere.
Age at death calculator example

How to use the age at death calculator

  1. Open the tab “Age from two dates”. Under “Date of birth” enter the day, choose the month and enter the year.
  2. Under “Date of death” enter the same three parts. The page shows the age at once, with the example dates replaced as soon as you type.
  3. If you do not know the day, clear the “Day (optional)” box. If you do not know the month, choose “Unknown” as well. The result then shows “Age at death (range)” with “Minimum age” and “Maximum age”.
  4. Read the tiles. With two complete dates you see “Age at death”, “Total days”, “Total months” and “Total weeks”. Press “Copy result” for a one-line summary or “Download CSV” for a small file.
  5. To find a birth date from an age, open “Birth date from an age”. Enter the date of the record, then the “Age in years”. Fill “Months (optional)” or “Days (optional)” for a baby or a small child.
  6. Read “Birth year”, “Earliest possible birth date” and “Latest possible birth date”. Both dates are included.
  7. For a census or similar record where only the year is known, open “Birth year from a record”. Enter the year, optionally the month, the age and, if the age was only an estimate, how many years it may be off by.

How is age at death calculated?

The calculator counts whole months from the birth date to the death date and then the days left over. A person’s age goes up on the birthday, so someone born on 12 March 1921 who died on 3 June 1994 was 73 years, 2 months and 22 days old: 12 May 1994 is exactly 73 years and 2 months after the birth, and 22 days remain until 3 June.

What happens with 29 February and the 31st?

When a month is shorter than the birth day, the day moves back to the last day of that month. A person born on 31 January reaches one month on 28 February, and a person born on 29 February has the birthday on 28 February in years that are not leap years. Other rules exist, such as using 1 March, so check which one a legal document needs.

How do I figure out birth year from age?

A person aged 34 on 1 June 1900 has had 34 birthdays but not the 35th. So they were born after 1 June 1865 and on or before 1 June 1866: from 2 June 1865 to 1 June 1866. That is why one record gives two possible birth years, here 1865 and 1866. Adding months or days to the age shrinks the range. If you only know the year of the record, the range grows by the length of that year, so aged 45 in 1921 gives 1875 or 1876.

What if the day or month is missing?

An incomplete date stands for every day it could be. The minimum age uses the latest possible birth and the earliest possible death, the maximum uses the earliest birth and the latest death. A birth in 1921 and a death on 3 June 1994 give 72 years, 5 months, 3 days to 73 years, 5 months, 2 days.

Which calendar is used?

Dates are Gregorian. England and its colonies changed in September 1752, so older dates there may be Julian. Convert them first, then enter the Gregorian date. A death on 2 September 1752 in England is the last day of the old calendar there, so check the source before you trust a date near the change.

Frequently asked questions

How do I calculate age at death from a gravestone or death record?

Enter the birth and death dates on the first tab. If the stone says only “aged 73”, use the second tab with the death date and 73 years to see the possible birth dates.

Why does the calculator give two birth years?

Because an age in whole years covers a stretch of 365 or 366 days. Unless the birthday is known, the person was born in one of two calendar years.

Can I use it for a date that is not a death?

Yes. The record date can be a census, a baptism, a marriage or any other event. The age is simply the age on that date.

What does the age range mean when a date is incomplete?

It is the youngest and the oldest the person could have been. The true age lies between the two, and every age in between is possible.

Does it work for babies?

Yes. Enter 0 years and the months or days from the record, such as 6 months or 10 days. The birth range then covers only a few weeks or a single day.

Is my data stored?

No. The calculation runs in your browser and nothing is uploaded.