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
- 3 Your mother
- 6 Your mother's father
- 12 Your mother's father's father
- 25 Your mother's father's father's mother
- 50 Your mother's father's father's mother's father
- 100 Your mother's father's father's mother's father's father
- 200 Your mother's father's father's mother's father's father's father
- 400 Your mother's father's father's mother's father's father's father's father
- 801 Your mother's father's father's mother's father's father's father's father's mother
- 1603 Your mother's father's father's mother's father's father's father's father's mother's mother
- 3206 Your mother's father's father's mother's father's father's father's father's mother's mother's father
- 6412 Your mother's father's father's mother's father's father's father's father's mother's mother's father's father
- 12825 Your mother's father's father's mother's father's father's father's father's mother's mother's father's father's mother
- 25650 Your mother's father's father's mother's father's father's father's father's mother's mother's father's father's mother's father
- 51301 Your mother's father's father's mother's father's father's father's father's mother's mother's father's father's mother's father's mother
- 102603 Your mother's father's father's mother's father's father's father's father's mother's mother's father's father's mother's father's mother's mother
- 205207 Your mother's father's father's mother's father's father's father's father's mother's mother's father's father's mother's father's mother's mother's mother
- 410415 Your mother's father's father's mother's father's father's father's father's mother's mother's father's father's mother's father's mother's mother's mother's mother
- 820831 Your mother's father's father's mother's father's father's father's father's mother's mother's father's father's mother's father's mother's mother's mother's mother's mother
Your mother's father's father's mother's father's father's father's father's mother's mother's father's father's mother's father's mother's mother's mother's mother's mother, a 17x great-grandmother, is number 820831.