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
- 1021 Your mother's mother's mother's mother's mother's mother's mother's father's mother
- 2043 Your mother's mother's mother's mother's mother's mother's mother's father's mother's mother
- 4086 Your mother's mother's mother's mother's mother's mother's mother's father's mother's mother's father
- 8173 Your mother's mother's mother's mother's mother's mother's mother's father's mother's mother's father's mother
- 16347 Your mother's mother's mother's mother's mother's mother's mother's father's mother's mother's father's mother's mother
- 32694 Your mother's mother's mother's mother's mother's mother's mother's father's mother's mother's father's mother's mother's father
- 65389 Your mother's mother's mother's mother's mother's mother's mother's father's mother's mother's father's mother's mother's father's mother
- 130779 Your mother's mother's mother's mother's mother's mother's mother's father's mother's mother's father's mother's mother's father's mother's mother
- 261559 Your mother's mother's mother's mother's mother's mother's mother's father's mother's mother's father's mother's mother's father's mother's mother's mother
- 523119 Your mother's mother's mother's mother's mother's mother's mother's father's mother's mother's father's mother's mother's father's mother's mother's mother's mother
- 1046238 Your mother's mother's mother's mother's mother's mother's mother's father's mother's mother's father's mother's mother's father's mother's mother's mother's mother's father
- 2092477 Your mother's mother's mother's mother's mother's mother's mother's father's mother's mother's father's mother's mother's father's mother's mother's mother's mother's father's mother
- 4184954 Your mother's mother's mother's mother's mother's mother's mother's father's mother's mother's father's mother's mother's father's mother's mother's mother's mother's father's mother's father
- 8369909 Your mother's mother's mother's mother's mother's mother's mother's father's mother's mother's father's mother's mother's father's mother's mother's mother's mother's father's mother's father's mother
- 16739819 Your mother's mother's mother's mother's mother's mother's mother's father's mother's mother's father's mother's mother's father's mother's mother's mother's mother's father's mother's father's mother's mother
Your mother's mother's mother's mother's mother's mother's mother's father's mother's mother's father's mother's mother's father's mother's mother's mother's mother's father's mother's father's mother's mother, a 21x great-grandmother, is number 16739819.