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
- 79 Your father's father's mother's mother's mother's mother
- 158 Your father's father's mother's mother's mother's mother's father
- 317 Your father's father's mother's mother's mother's mother's father's mother
- 635 Your father's father's mother's mother's mother's mother's father's mother's mother
- 1270 Your father's father's mother's mother's mother's mother's father's mother's mother's father
- 2540 Your father's father's mother's mother's mother's mother's father's mother's mother's father's father
- 5080 Your father's father's mother's mother's mother's mother's father's mother's mother's father's father's father
- 10161 Your father's father's mother's mother's mother's mother's father's mother's mother's father's father's father's mother
- 20323 Your father's father's mother's mother's mother's mother's father's mother's mother's father's father's father's mother's mother
- 40647 Your father's father's mother's mother's mother's mother's father's mother's mother's father's father's father's mother's mother's mother
- 81294 Your father's father's mother's mother's mother's mother's father's mother's mother's father's father's father's mother's mother's mother's father
- 162589 Your father's father's mother's mother's mother's mother's father's mother's mother's father's father's father's mother's mother's mother's father's mother
- 325179 Your father's father's mother's mother's mother's mother's father's mother's mother's father's father's father's mother's mother's mother's father's mother's mother
- 650359 Your father's father's mother's mother's mother's mother's father's mother's mother's father's father's father's mother's mother's mother's father's mother's mother's mother
- 1300719 Your father's father's mother's mother's mother's mother's father's mother's mother's father's father's father's mother's mother's mother's father's mother's mother's mother's mother
- 2601438 Your father's father's mother's mother's mother's mother's father's mother's mother's father's father's father's mother's mother's mother's father's mother's mother's mother's mother's father
- 5202877 Your father's father's mother's mother's mother's mother's father's mother's mother's father's father's father's mother's mother's mother's father's mother's mother's mother's mother's father's mother
- 10405755 Your father's father's mother's mother's mother's mother's father's mother's mother's father's father's father's mother'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 mother's father's mother's mother's father's father's father's mother'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 10405755.