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
- 126 Your mother's mother's mother's mother's mother's father
- 253 Your mother's mother's mother's mother's mother's father's mother
- 507 Your mother's mother's mother's mother's mother's father's mother's mother
- 1015 Your mother's mother's mother's mother's mother's father's mother's mother's mother
- 2031 Your mother's mother's mother's mother's mother's father's mother's mother's mother's mother
- 4062 Your mother's mother's mother's mother's mother's father's mother's mother's mother's mother's father
- 8125 Your mother's mother's mother's mother's mother's father's mother's mother's mother's mother's father's mother
- 16251 Your mother's mother's mother's mother's mother's father's mother's mother's mother's mother's father's mother's mother
- 32502 Your mother's mother's mother's mother's mother's father's mother's mother's mother's mother's father's mother's mother's father
- 65004 Your mother's mother's mother's mother's mother's father's mother's mother's mother's mother's father's mother's mother's father's father
- 130008 Your mother's mother's mother's mother's mother's father's mother's mother's mother's mother's father's mother's mother's father's father's father
- 260017 Your mother's mother's mother's mother's mother's father's mother's mother's mother's mother's father's mother's mother's father's father's father's mother
- 520035 Your mother's mother's mother's mother's mother's father's mother's mother's mother's mother's father's mother's mother's father's father's father's mother's mother
- 1040070 Your mother's mother's mother's mother's mother's father's mother's mother's mother's mother's father's mother's mother's father's father's father's mother's mother's father
- 2080140 Your mother's mother's mother's mother's mother's father's mother's mother's mother's mother's father's mother's mother's father's father's father's mother's mother's father's father
- 4160281 Your mother's mother's mother's mother's mother's father's mother's mother's mother's mother's father's mother's mother's father's father's father's mother's mother's father's father's mother
- 8320563 Your mother's mother's mother's mother's mother's father's mother's mother's mother's mother's father's mother's mother's father's father's father's mother's mother's father's father's mother's mother
- 16641127 Your mother's mother's mother's mother's mother's father's mother's mother's mother's mother's father's mother's mother's father's father's father's mother's mother's father's father's mother's mother's mother
Your mother's mother's mother's mother's mother's father's mother's mother's mother's mother's father's mother's mother's father's father's father's mother's mother's father's father's mother's mother's mother, a 21x great-grandmother, is number 16641127.