Dealing with Missing Dates and Uncertain Information in Your Family Tree

How to record approximate, calculated and unknown dates in a family tree so that your charts and books stay honest, sortable and useful.

No family tree is complete. Somewhere there is a great-great-grandmother with no birth date, a marriage that happened sometime before 1880, and a death that you know only from a widow's remarriage. How you record these gaps decides whether your charts and books remain trustworthy.

The GEDCOM date vocabulary

The GEDCOM standard has a small vocabulary for uncertainty, and every serious program supports it:

• ABT 1850 — about 1850, an estimate.
• CAL 1850 — calculated, for example from an age at death.
• EST 1850 — estimated from other evidence, such as the birth of a first child.
• BEF 1880 and AFT 1875 — before and after.
• BET 1848 AND 1852 — between two dates.
• 1850 alone — a year without a day and month, which is a plain date, not an estimate.

Use these instead of writing c. or a question mark inside the date field. Programs can sort and calculate with the standard qualifiers; they cannot with free text.

Never invent precision

A date of 1 January 1850 because the program demanded a full date is worse than no date at all. Record the year alone, or ABT with the year, and put the reasoning in a note: born about 1850, aged 31 in the 1881 census.

Where the estimate comes from

Write down how you arrived at an estimate. Typical sources:

• Age in a census, death record or gravestone (calculated dates).
• Age at marriage in the marriage register.
• First child born about a year after the marriage.
• Military conscription lists, which give the year of birth.

A note such as estimated from the age of 47 at burial in 1897 lets a later researcher, or your future self, judge the estimate.

Unknown names

Leave the given name empty and record only the surname, or record only the given name if that is what you have. Do not write Unknown or Mrs Smith in the name field. Empty fields tell the truth; placeholders spread.

How charts handle gaps

A chart can only show what you recorded. PrintFamilyTree prints a birth year with an asterisk (\ 1850*) and a death year with a dash; an estimated date is shown as about 1850. When some siblings have birth dates and others do not, they are drawn in the order of your file rather than sorted by date, so that an unknown date never moves a child to the wrong place. If the sex of a person is not recorded, the box is grey instead of blue or rose.

How books handle gaps

In a book, an unknown date is simply not printed, and an estimate is printed with the qualifier. Good narrative text says she was born about 1850, probably in Kraków rather than pretending certainty. Reserve firm statements for facts with a source.

Turn gaps into a research list

Each empty field is a task. Once a year, generate a list of people without birth dates or without parents and pick the three closest to you. Filling the gaps that matter most is more satisfying than adding another distant cousin, and it makes every printed chart a little more complete.