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
- 19 Your father's father's mother's mother
- 39 Your father's father's mother's mother's mother
- 78 Your father's father's mother's mother's mother's father
- 156 Your father's father's mother's mother's mother's father's father
- 312 Your father's father's mother's mother's mother's father's father's father
- 625 Your father's father's mother's mother's mother's father's father's father's mother
- 1251 Your father's father's mother's mother's mother's father's father's father's mother's mother
- 2503 Your father's father's mother's mother's mother's father's father's father's mother's mother's mother
- 5007 Your father's father's mother's mother's mother's father's father's father's mother's mother's mother's mother
- 10015 Your father's father's mother's mother's mother's father's father's father's mother's mother's mother's mother's mother
- 20030 Your father's father's mother's mother's mother's father's father's father's mother's mother's mother's mother's mother's father
- 40061 Your father's father's mother's mother's mother's father's father's father's mother's mother's mother's mother's mother's father's mother
- 80123 Your father's father's mother's mother's mother's father's father's father's mother's mother's mother's mother's mother's father's mother's mother
- 160246 Your father's father's mother's mother's mother's father's father's father's mother's mother's mother's mother's mother's father's mother's mother's father
- 320492 Your father's father's mother's mother's mother's father's father's father's mother's mother's mother's mother's mother's father's mother's mother's father's father
- 640984 Your father's father's mother's mother's mother's father's father's father's mother's mother's mother's mother's mother's father's mother's mother's father's father's father
- 1281969 Your father's father's mother's mother's mother's father's father's father's mother's mother's mother's mother's mother's father's mother's mother's father's father's father's mother
- 2563939 Your father's father's mother's mother's mother's father's father's father's mother's mother's mother's mother's mother's father's mother's mother's father's father's father's mother's mother
- 5127879 Your father's father's mother's mother's mother's father's father's father's mother'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 mother
- 10255758 Your father's father's mother's mother's mother's father's father's father's mother'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 mother's father
Your father's father's mother's mother's mother's father's father's father's mother'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 mother's father, a 21x great-grandfather, is number 10255758.