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
- 18 Your father's father's mother's father
- 36 Your father's father's mother's father's father
- 72 Your father's father's mother's father's father's father
- 145 Your father's father's mother's father's father's father's mother
- 291 Your father's father's mother's father's father's father's mother's mother
- 582 Your father's father's mother's father's father's father's mother's mother's father
- 1164 Your father's father's mother's father's father's father's mother's mother's father's father
- 2329 Your father's father's mother's father's father's father's mother's mother's father's father's mother
- 4659 Your father's father's mother's father's father's father's mother's mother's father's father's mother's mother
- 9318 Your father's father's mother's father's father's father's mother's mother's father's father's mother's mother's father
- 18637 Your father's father's mother's father's father's father's mother's mother's father's father's mother's mother's father's mother
- 37275 Your father's father's mother's father's father's father's mother's mother's father's father's mother's mother's father's mother's mother
- 74550 Your father's father's mother's father's father's father's mother's mother's father's father's mother's mother's father's mother's mother's father
- 149101 Your father's father's mother's father's father's father's mother's mother's father's father's mother's mother's father's mother's mother's father's mother
- 298202 Your father's father's mother's father's father's father's mother's mother's father's father's mother's mother's father's mother's mother's father's mother's father
- 596404 Your father's father's mother's father's father's father's mother's mother's father's father's mother's mother's father's mother's mother's father's mother's father's father
- 1192808 Your father's father's mother's father's father's father's mother's mother's father's father's mother's mother's father's mother's mother's father's mother's father's father's father
Your father's father's mother's father's father's father's mother's mother's father's father's mother's mother's father's mother's mother's father's mother's father's father's father, a 18x great-grandfather, is number 1192808.