ahnentafel

Ahnentafel is a genealogical numbering system used for listing a person’s ancestors in a fixed, tree-like order. The term comes from German, meaning “ancestor table.” In this system, the person of interest is assigned the number 1. The father of the person numbered n is 2n, and the mother is 2n+1. As a result, generation increases with the numeric value, and the structure forms a binary tree that can be traced by simple arithmetic.

A typical Ahnentafel lists each ancestor with essential information such as name, birth and death dates, and places, and often includes sources and notes. The format is widely used in genealogical research and is compatible with many software programs, printed pedigrees, and online family trees. Because the numbering encodes the direct paternal and maternal links, the table allows quick navigation to a given ancestor and facilitates automated data processing.

Ahnentafel is commonly used as a companion to pedigree charts. It provides a compact, machine-readable way to organize known ancestors and to derive generation and parental relationships from a single number. The system covers ancestors only and does not depict descendants. In modern genealogy, Ahnentafel numbers are one of several standardized indexing methods employed to structure and exchange genealogical data.