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
- 2 Your father
- 4 Your father's father
- 8 Your father's father's father
- 17 Your father's father's father's mother
- 35 Your father's father's father's mother's mother
- 70 Your father's father's father's mother's mother's father
- 140 Your father's father's father's mother's mother's father's father
- 280 Your father's father's father's mother's mother's father's father's father
- 560 Your father's father's father's mother's mother's father's father's father's father
- 1120 Your father's father's father's mother's mother's father's father's father's father's father
- 2240 Your father's father's father's mother's mother's father's father's father's father's father's father
- 4480 Your father's father's father's mother's mother's father's father's father's father's father's father's father
- 8961 Your father's father's father's mother's mother's father's father's father's father's father's father's father's mother
- 17923 Your father's father's father's mother's mother's father's father's father's father's father's father's father's mother's mother
- 35847 Your father's father's father's mother's mother's father's father's father's father's father's father's father's mother's mother's mother
- 71694 Your father's father's father's mother's mother's father's father's father's father's father's father's father's mother's mother's mother's father
- 143389 Your father's father's father's mother's mother's father's father's father's father's father's father's father's mother's mother's mother's father's mother
Your father's father's father's mother's mother's father's father's father's father's father's father's father's mother's mother's mother's father's mother, a 15x great-grandmother, is number 143389.