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
- 38 Your father's father's mother's mother's father
- 76 Your father's father's mother's mother's father's father
- 153 Your father's father's mother's mother's father's father's mother
- 307 Your father's father's mother's mother's father's father's mother's mother
- 614 Your father's father's mother's mother's father's father's mother's mother's father
- 1228 Your father's father's mother's mother's father's father's mother's mother's father's father
- 2456 Your father's father's mother's mother's father's father's mother's mother's father's father's father
- 4913 Your father's father's mother's mother's father's father's mother's mother's father's father's father's mother
- 9827 Your father's father's mother's mother's father's father's mother's mother's father's father's father's mother's mother
- 19655 Your father's father's mother's mother's father's father's mother's mother's father's father's father's mother's mother's mother
- 39311 Your father's father's mother's mother's father's father's mother's mother's father's father's father's mother's mother's mother's mother
- 78622 Your father's father's mother's mother's father's father's mother's mother's father's father's father's mother's mother's mother's mother's father
- 157244 Your father's father's mother's mother's father's father's mother's mother's father's father's father's mother's mother's mother's mother's father's father
- 314488 Your father's father's mother's mother's father's father's mother's mother's father's father's father's mother's mother's mother's mother's father's father's father
- 628977 Your father's father's mother's mother's father's father's mother's mother's father's father's father's mother's mother's mother's mother's father's father's father's mother
- 1257955 Your father's father's mother's mother's father's father's mother's mother's father's father's father's mother's mother's mother's mother's father's father's father's mother's mother
- 2515910 Your father's father's mother's mother's father's father's mother's mother's father's father's father's mother's mother's mother's mother's father's father's father's mother's mother's father
- 5031821 Your father's father's mother's mother's father's father's mother's mother's father's father's father's mother's mother's mother's mother's father's father's father's mother's mother's father's mother
Your father's father's mother's mother's father's father's mother's mother's father's father's father's mother's mother's mother's mother's father's father's father's mother's mother's father's mother, a 20x great-grandmother, is number 5031821.