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
- 10 Your father's mother's father
- 21 Your father's mother's father's mother
- 42 Your father's mother's father's mother's father
- 85 Your father's mother's father's mother's father's mother
- 170 Your father's mother's father's mother's father's mother's father
- 341 Your father's mother's father's mother's father's mother's father's mother
- 683 Your father's mother's father's mother's father's mother's father's mother's mother
- 1367 Your father's mother's father's mother's father's mother's father's mother's mother's mother
- 2735 Your father's mother's father's mother's father's mother's father's mother's mother's mother's mother
- 5470 Your father's mother's father's mother's father's mother's father's mother's mother's mother's mother's father
- 10941 Your father's mother's father's mother's father's mother's father's mother's mother's mother's mother's father's mother
- 21883 Your father's mother's father's mother's father's mother's father's mother's mother's mother's mother's father's mother's mother
- 43767 Your father's mother's father's mother's father's mother's father's mother's mother's mother's mother's father's mother's mother's mother
- 87534 Your father's mother's father's mother's father's mother's father's mother's mother's mother's mother's father's mother's mother's mother's father
- 175069 Your father's mother's father's mother's father's mother's father's mother's mother's mother's mother's father's mother's mother's mother's father's mother
- 350138 Your father's mother's father's mother's father's mother's father's mother's mother's mother's mother's father's mother's mother's mother's father's mother's father
- 700276 Your father's mother's father's mother's father's mother's father's mother's mother's mother's mother's father's mother's mother's mother's father's mother's father's father
Your father's mother's father's mother's father's mother's father's mother's mother's mother's mother's father's mother's mother's mother's father's mother's father's father, a 17x great-grandfather, is number 700276.