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
- 5 Your father's mother
- 11 Your father's mother's mother
- 22 Your father's mother's mother's father
- 45 Your father's mother's mother's father's mother
- 90 Your father's mother's mother's father's mother's father
- 181 Your father's mother's mother's father's mother's father's mother
- 362 Your father's mother's mother's father's mother's father's mother's father
- 725 Your father's mother's mother's father's mother's father's mother's father's mother
- 1450 Your father's mother's mother's father's mother's father's mother's father's mother's father
- 2900 Your father's mother's mother's father's mother's father's mother's father's mother's father's father
- 5800 Your father's mother's mother's father's mother's father's mother's father's mother's father's father's father
- 11600 Your father's mother's mother's father's mother's father's mother's father's mother's father's father's father's father
- 23200 Your father's mother's mother's father's mother's father's mother's father's mother's father's father's father's father's father
- 46400 Your father's mother's mother's father's mother's father's mother's father's mother's father's father's father's father's father's father
- 92801 Your father's mother's mother's father's mother's father's mother's father's mother's father's father's father's father's father's father's mother
- 185602 Your father's mother's mother's father's mother's father's mother's father's mother's father's father's father's father's father's father's mother's father
- 371204 Your father's mother's mother's father's mother's father's mother's father's mother's father's father's father's father's father's father's mother's father's father
- 742408 Your father's mother's mother's father's mother's father's mother's father's mother's father's father's father's father's father's father's mother's father's father's father
- 1484817 Your father's mother's mother's father's mother's father's mother's father's mother's father's father's father's father's father's father's mother's father's father's father's mother
Your father's mother's mother's father's mother's father's mother's father's mother's father's father's father's father's father's father's mother's father's father's father's mother, a 18x great-grandmother, is number 1484817.