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
- 77 Your father's father's mother's mother's father's mother
- 155 Your father's father's mother's mother's father's mother's mother
- 311 Your father's father's mother's mother's father's mother's mother's mother
- 623 Your father's father's mother's mother's father's mother's mother's mother's mother
- 1247 Your father's father's mother's mother's father's mother's mother's mother's mother's mother
- 2494 Your father's father's mother's mother's father's mother's mother's mother's mother's mother's father
- 4989 Your father's father's mother's mother's father's mother's mother's mother's mother's mother's father's mother
- 9979 Your father's father's mother's mother's father's mother's mother's mother's mother's mother's father's mother's mother
- 19959 Your father's father's mother's mother's father's mother's mother's mother's mother's mother's father's mother's mother's mother
- 39918 Your father's father's mother's mother's father's mother's mother's mother's mother's mother's father's mother's mother's mother's father
- 79837 Your father's father's mother's mother's father's mother's mother's mother's mother's mother's father's mother's mother's mother's father's mother
- 159675 Your father's father's mother's mother's father's mother's mother's mother's mother's mother's father's mother's mother's mother's father's mother's mother
- 319350 Your father's father's mother's mother's father's mother's mother's mother's mother's mother's father's mother's mother's mother's father's mother's mother's father
- 638700 Your father's father's mother's mother's father's mother's mother's mother's mother's mother's father's mother's mother's mother's father's mother's mother's father's father
- 1277400 Your father's father's mother's mother's father's mother's mother's mother's mother's mother's father's mother's mother's mother's father's mother's mother's father's father's father
- 2554800 Your father's father's mother's mother's father's mother's mother's mother's mother's mother's father's mother's mother's mother's father's mother's mother's father's father's father's father
- 5109601 Your father's father's mother's mother's father's mother's mother's mother's mother's mother's father's mother's mother's mother's father's mother's mother's father's father's father's father's mother
- 10219202 Your father's father's mother's mother's father's mother's mother's mother's mother's mother's father's mother's mother's mother's father's mother's mother's father's father's father's father's mother's father
Your father's father's mother's mother's father's mother's mother's mother's mother's mother's father's mother's mother's mother's father's mother's mother's father's father's father's father's mother's father, a 21x great-grandfather, is number 10219202.