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
- 62 Your mother's mother's mother's mother's father
- 125 Your mother's mother's mother's mother's father's mother
- 250 Your mother's mother's mother's mother's father's mother's father
- 500 Your mother's mother's mother's mother's father's mother's father's father
- 1000 Your mother's mother's mother's mother's father's mother's father's father's father
- 2000 Your mother's mother's mother's mother's father's mother's father's father's father's father
- 4001 Your mother's mother's mother's mother's father's mother's father's father's father's father's mother
- 8002 Your mother's mother's mother's mother's father's mother's father's father's father's father's mother's father
- 16005 Your mother's mother's mother's mother's father's mother's father's father's father's father's mother's father's mother
- 32011 Your mother's mother's mother's mother's father's mother's father's father's father's father's mother's father's mother's mother
- 64023 Your mother's mother's mother's mother's father's mother's father's father's father's father's mother's father's mother's mother's mother
- 128047 Your mother's mother's mother's mother's father's mother's father's father's father's father's mother's father's mother's mother's mother's mother
- 256094 Your mother's mother's mother's mother's father's mother's father's father's father's father's mother's father's mother's mother's mother's mother's father
- 512188 Your mother's mother's mother's mother's father's mother's father's father's father's father's mother's father's mother's mother's mother's mother's father's father
- 1024377 Your mother's mother's mother's mother's father's mother's father's father's father's father's mother's father's mother's mother's mother's mother's father's father's mother
- 2048754 Your mother's mother's mother's mother's father's mother's father's father's father's father's mother's father's mother's mother's mother's mother's father's father's mother's father
Your mother's mother's mother's mother's father's mother's father's father's father's father's mother's father's mother's mother's mother's mother's father's father's mother's father, a 18x great-grandfather, is number 2048754.