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
- 33 Your father's father's father's father's mother
- 66 Your father's father's father's father's mother's father
- 133 Your father's father's father's father's mother's father's mother
- 267 Your father's father's father's father's mother's father's mother's mother
- 535 Your father's father's father's father's mother's father's mother's mother's mother
- 1071 Your father's father's father's father's mother's father's mother's mother's mother's mother
- 2142 Your father's father's father's father's mother's father's mother's mother's mother's mother's father
- 4284 Your father's father's father's father's mother's father's mother's mother's mother's mother's father's father
- 8568 Your father's father's father's father's mother's father's mother's mother's mother's mother's father's father's father
- 17137 Your father's father's father's father's mother's father's mother's mother's mother's mother's father's father's father's mother
- 34275 Your father's father's father's father's mother's father's mother's mother's mother's mother's father's father's father's mother's mother
- 68550 Your father's father's father'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
- 137101 Your father's father's father'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 mother
- 274203 Your father's father's father'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 mother's mother
- 548407 Your father's father's father'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 mother's mother's mother
- 1096814 Your father's father's father'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 mother's mother's mother's father
- 2193628 Your father's father's father'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 mother's mother's mother's father's father
- 4387256 Your father's father's father'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 mother's mother's mother's father's father's father
Your father's father's father'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 mother's mother's mother's father's father's father, a 20x great-grandfather, is number 4387256.