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
- 3 Your mother
- 7 Your mother's mother
- 15 Your mother's mother's mother
- 31 Your mother's mother's mother's mother
- 63 Your mother's mother's mother's mother's mother
- 127 Your mother's mother's mother's mother's mother's mother
- 255 Your mother's mother's mother's mother's mother's mother's mother
- 510 Your mother's mother's mother's mother's mother's mother's mother's father
- 1020 Your mother's mother's mother's mother's mother's mother's mother's father's father
- 2041 Your mother's mother's mother's mother's mother's mother's mother's father's father's mother
- 4082 Your mother's mother's mother's mother's mother's mother's mother's father's father's mother's father
- 8165 Your mother's mother's mother's mother's mother's mother's mother's father's father's mother's father's mother
- 16331 Your mother's mother's mother's mother's mother's mother's mother's father's father's mother's father's mother's mother
- 32663 Your mother's mother's mother's mother's mother's mother's mother's father's father's mother's father's mother's mother's mother
- 65327 Your mother's mother's mother's mother's mother's mother's mother's father's father's mother's father's mother's mother's mother's mother
- 130654 Your mother's mother's mother's mother's mother's mother's mother's father's father's mother's father's mother's mother's mother's mother's father
- 261309 Your mother's mother's mother's mother's mother's mother's mother's father's father's mother's father's mother's mother's mother's mother's father's mother
- 522619 Your mother's mother's mother's mother's mother's mother's mother's father's father's mother's father's mother's mother's mother's mother's father's mother's mother
- 1045238 Your mother's mother's mother's mother's mother's mother's mother's father's father's mother's father's mother's mother's mother's mother's father's mother's mother's father
- 2090476 Your mother's mother's mother's mother's mother's mother's mother's father's father's mother's father's mother's mother's mother's mother's father's mother's mother's father's father
- 4180953 Your mother's mother's mother's mother's mother's mother's mother's father's father's mother's father's mother's mother's mother's mother's father's mother's mother's father's father's mother
- 8361906 Your mother's mother's mother's mother's mother's mother's mother's father's father's mother's father's mother's mother's mother's mother's father's mother's mother's father's father's mother's father
Your mother's mother's mother's mother's mother's mother's mother's father's father's mother's father's mother's mother's mother's mother's father's mother's mother's father's father's mother's father, a 20x great-grandfather, is number 8361906.