Ancestor Numbers
An Ancestor Number (the proper name is an Ahnentafel number) says exactly where a direct ancestor sits in your family tree. You are always number 1. Anyone's father has double their number, and their mother double plus one: so your father is 2 and your mother 3, your father's parents are 4 and 5, your mother's parents 6 and 7, and so on. That's why every man in your tree (apart from you) has an even number and every woman an odd one.
Entering the Ancestor Numbers of your direct ancestors on My Ancestors keeps your records accurate, helps your cousins work out how they're related to you, and tells apart two lines that happen to share a surname.
Print our Ancestor Chart Every box on the chart shows its number, five generations back from you.
Peter Calver, who founded LostCousins, explained Ancestor Numbers in his newsletter of 25 December 2023 (Why are your female ancestors odd?).
Find a number by stepping back from you
Choose father or mother, one generation at a time, until you reach the person you want.
- 1 You
- 2 Your father
- 4 Your father's father
- 9 Your father's father's mother
- 19 Your father's father's mother's mother
- 39 Your father's father's mother's mother's mother
- 78 Your father's father's mother's mother's mother's father
- 157 Your father's father's mother's mother's mother's father's mother
- 315 Your father's father's mother's mother's mother's father's mother's mother
- 631 Your father's father's mother's mother's mother's father's mother's mother's mother
- 1263 Your father's father's mother's mother's mother's father's mother's mother's mother's mother
- 2527 Your father's father's mother's mother's mother's father's mother's mother's mother's mother's mother
- 5055 Your father's father's mother's mother's mother's father's mother's mother's mother's mother's mother's mother
- 10110 Your father's father's mother's mother's mother's father's mother's mother's mother's mother's mother's mother's father
- 20221 Your father's father's mother's mother's mother's father's mother's mother's mother's mother's mother's mother's father's mother
- 40443 Your father's father's mother's mother's mother's father's mother's mother's mother's mother's mother's mother's father's mother's mother
- 80886 Your father's father's mother's mother's mother's father's mother's mother's mother's mother's mother's mother's father's mother's mother's father
- 161773 Your father's father's mother's mother's mother's father's mother's mother's mother's mother's mother's mother's father's mother's mother's father's mother
- 323547 Your father's father's mother's mother's mother's father's mother's mother's mother's mother's mother's mother's father's mother's mother's father's mother's mother
- 647095 Your father's father's mother's mother's mother's father's mother's mother's mother's mother's mother's mother's father's mother's mother's father's mother's mother's mother
- 1294191 Your father's father's mother's mother's mother's father's mother's mother's mother's mother's mother's mother's father's mother's mother's father's mother's mother's mother's mother
- 2588382 Your father's father's mother's mother's mother's father's mother's mother's mother's mother's mother's mother's father's mother's mother's father's mother's mother's mother's mother's father
- 5176765 Your father's father's mother's mother's mother's father's mother's mother's mother's mother's mother's mother's father's mother's mother's father's mother's mother's mother's mother's father's mother
- 10353531 Your father's father's mother's mother's mother's father's mother's mother's mother's mother's mother's mother's father's mother's mother's father's mother's mother's mother's mother's father's mother's mother
Your father's father's mother's mother's mother's father's mother's mother's mother's mother's mother's mother's father's mother's mother's father's mother's mother's mother's mother's father's mother's mother, a 21x great-grandmother, is number 10353531.