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
- 9 Your father's father's mother
- 18 Your father's father's mother's father
- 36 Your father's father's mother's father's father
- 72 Your father's father's mother's father's father's father
- 144 Your father's father's mother's father's father's father's father
- 288 Your father's father's mother's father's father's father's father's father
- 577 Your father's father's mother's father's father's father's father's father's mother
- 1155 Your father's father's mother's father's father's father's father's father's mother's mother
- 2310 Your father's father's mother's father's father's father's father's father's mother's mother's father
- 4621 Your father's father's mother's father's father's father's father's father's mother's mother's father's mother
- 9243 Your father's father's mother's father's father's father's father's father's mother's mother's father's mother's mother
- 18487 Your father's father's mother's father's father's father's father's father's mother's mother's father's mother's mother's mother
- 36974 Your father's father's mother's father's father's father's father's father's mother's mother's father's mother's mother's mother's father
- 73949 Your father's father's mother's father's father's father's father's father's mother's mother's father's mother's mother's mother's father's mother
- 147899 Your father's father's mother's father's father's father's father's father's mother's mother's father's mother's mother's mother's father's mother's mother
- 295798 Your father's father's mother's father's father's father's father's father's mother's mother's father's mother's mother's mother's father's mother's mother's father
- 591597 Your father's father's mother's father's father's father's father's father's mother's mother's father's mother's mother's mother's father's mother's mother's father's mother
- 1183194 Your father's father's mother's father's father's father's father's father's mother's mother's father's mother's mother's mother's father's mother's mother's father's mother's father
- 2366389 Your father's father's mother's father's father's father's father's father's mother's mother's father's mother's mother's mother's father's mother's mother's father's mother's father's mother
- 4732779 Your father's father's mother's father's father's father's father's father's mother's mother's father's mother's mother's mother's father's mother's mother's father's mother's father's mother's mother
Your father's father's mother's father's father's father's father's father's mother's mother's father's mother's mother's mother's father's mother's mother's father's mother's father's mother's mother, a 20x great-grandmother, is number 4732779.