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
- 30 Your mother's mother's mother's father
- 61 Your mother's mother's mother's father's mother
- 123 Your mother's mother's mother's father's mother's mother
- 246 Your mother's mother's mother's father's mother's mother's father
- 493 Your mother's mother's mother's father's mother's mother's father's mother
- 987 Your mother's mother's mother's father's mother's mother's father's mother's mother
- 1975 Your mother's mother's mother's father's mother's mother's father's mother's mother's mother
- 3950 Your mother's mother's mother's father's mother's mother's father's mother's mother's mother's father
- 7900 Your mother's mother's mother's father's mother's mother's father's mother's mother's mother's father's father
- 15801 Your mother's mother's mother's father's mother's mother's father's mother's mother's mother's father's father's mother
- 31602 Your mother's mother's mother's father's mother's mother's father's mother's mother's mother's father's father's mother's father
- 63205 Your mother's mother's mother's father's mother's mother's father's mother's mother's mother's father's father's mother's father's mother
- 126411 Your mother's mother's mother's father's mother's mother's father's mother's mother's mother's father's father's mother's father's mother's mother
- 252823 Your mother's mother's mother's father's mother's mother's father's mother's mother's mother's father's father's mother's father's mother's mother's mother
Your mother's mother's mother's father's mother's mother's father's mother's mother's mother's father's father's mother's father's mother's mother's mother, a 15x great-grandmother, is number 252823.