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
- 8 Your father's father's father
- 16 Your father's father's father's father
- 32 Your father's father's father's father's father
- 64 Your father's father's father's father's father's father
- 129 Your father's father's father's father's father's father's mother
- 259 Your father's father's father's father's father's father's mother's mother
- 519 Your father's father's father's father's father's father's mother's mother's mother
- 1039 Your father's father's father's father's father's father's mother's mother's mother's mother
- 2078 Your father's father's father's father's father's father's mother's mother's mother's mother's father
- 4157 Your father's father's father's father's father's father's mother's mother's mother's mother's father's mother
- 8315 Your father's father's father's father's father's father's mother's mother's mother's mother's father's mother's mother
- 16630 Your father's father's father's father's father's father's mother's mother's mother's mother's father's mother's mother's father
- 33260 Your father's father's father's father's father's father's mother's mother's mother's mother's father's mother's mother's father's father
- 66521 Your father's father's father's father's father's father's mother's mother's mother's mother's father's mother's mother's father's father's mother
- 133042 Your father's father's father's father's father's father's mother's mother's mother's mother's father's mother's mother's father's father's mother's father
- 266084 Your father's father's father's father's father's father's mother's mother's mother's mother's father's mother's mother's father's father's mother's father's father
- 532169 Your father's father's father's father's father's father's mother's mother's mother's mother's father's mother's mother's father's father's mother's father's father's mother
Your father's father's father's father's father's father's mother's mother's mother's mother's father's mother's mother's father's father's mother's father's father's mother, a 17x great-grandmother, is number 532169.