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
- 6 Your mother's father
- 12 Your mother's father's father
- 25 Your mother's father's father's mother
- 51 Your mother's father's father's mother's mother
- 103 Your mother's father's father's mother's mother's mother
- 206 Your mother's father's father's mother's mother's mother's father
- 412 Your mother's father's father's mother's mother's mother's father's father
- 825 Your mother's father's father's mother's mother's mother's father's father's mother
- 1651 Your mother's father's father's mother's mother's mother's father's father's mother's mother
- 3303 Your mother's father's father's mother's mother's mother's father's father's mother's mother's mother
- 6606 Your mother's father's father's mother's mother's mother's father's father's mother's mother's mother's father
- 13212 Your mother's father's father's mother's mother's mother's father's father's mother's mother's mother's father's father
- 26425 Your mother's father's father's mother's mother's mother's father's father's mother's mother's mother's father's father's mother
- 52851 Your mother's father's father's mother's mother's mother's father's father's mother's mother's mother's father's father's mother's mother
- 105703 Your mother's father's father's mother's mother's mother's father's father's mother's mother's mother's father's father's mother's mother's mother
- 211407 Your mother's father's father's mother's mother's mother's father's father's mother's mother's mother's father's father's mother's mother's mother's mother
- 422814 Your mother's father's father's mother's mother's mother's father's father's mother's mother's mother's father's father's mother's mother's mother's mother's father
- 845628 Your mother's father's father's mother's mother's mother's father's father's mother's mother's mother's father's father's mother's mother's mother's mother's father's father
Your mother's father's father's mother's mother's mother's father's father's mother's mother's mother's father's father's mother's mother's mother's mother's father's father, a 17x great-grandfather, is number 845628.