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
- 171 Your father's mother's father's mother's father's mother's mother
- 343 Your father's mother's father's mother's father's mother's mother's mother
- 687 Your father's mother's father's mother's father's mother's mother's mother's mother
- 1374 Your father's mother's father's mother's father's mother's mother's mother's mother's father
- 2748 Your father's mother's father's mother's father's mother's mother's mother's mother's father's father
- 5496 Your father's mother's father's mother's father's mother's mother's mother's mother's father's father's father
- 10993 Your father's mother's father's mother's father's mother's mother's mother's mother's father's father's father's mother
- 21987 Your father's mother's father's mother's father's mother's mother's mother's mother's father's father's father's mother's mother
- 43974 Your father's mother's father's mother's father's mother's mother's mother's mother's father's father's father's mother's mother's father
- 87948 Your father's mother's father's mother's father's mother's mother's mother's mother's father's father's father's mother's mother's father's father
- 175896 Your father's mother's father's mother's father's mother's mother's mother's mother's father's father's father's mother's mother's father's father's father
- 351793 Your father's mother's father's mother's father's mother's mother's mother's mother's father's father's father's mother's mother's father's father's father's mother
- 703587 Your father's mother's father's mother's father's mother's mother's mother's mother's father's father's father's mother's mother's father's father's father's mother's mother
Your father's mother's father's mother's father's mother's mother's mother's mother's father's father's father's mother's mother's father's father's father's mother's mother, a 17x great-grandmother, is number 703587.