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
- 16 Your father's father's father's father
- 32 Your father's father's father's father's father
- 64 Your father's father's father's father's father's father
- 129 Your father's father's father's father's father's father's mother
- 259 Your father's father's father's father's father's father's mother's mother
- 518 Your father's father's father's father's father's father's mother's mother's father
- 1037 Your father's father's father's father's father's father's mother's mother's father's mother
- 2075 Your father's father's father's father's father's father's mother's mother's father's mother's mother
- 4150 Your father's father's father's father's father's father's mother's mother's father's mother's mother's father
- 8301 Your father's father's father's father's father's father's mother's mother's father's mother's mother's father's mother
- 16603 Your father's father's father's father's father's father's mother's mother's father's mother's mother's father's mother's mother
- 33206 Your father's father's father's father's father's father's mother's mother's father's mother's mother's father's mother's mother's father
- 66413 Your father's father's father's father's father's father's mother's mother's father's mother's mother's father's mother's mother's father's mother
- 132827 Your father's father's father's father's father's father's mother's mother's father's mother's mother's father's mother's mother's father's mother's mother
- 265654 Your father's father's father's father's father's father's mother's mother's father's mother's mother's father's mother's mother's father's mother's mother's father
- 531308 Your father's father's father's father's father's father's mother's mother's father's mother's mother's father's mother's mother's father's mother's mother's father's father
- 1062616 Your father's father's father's father's father's father's mother's mother's father's mother's mother's father's mother's mother's father's mother's mother's father's father's father
- 2125233 Your father's father's father's father's father's father's mother's mother's father's mother's mother's father's mother's mother's father's mother's mother's father's father's father's mother
- 4250466 Your father's father's father's father's father's father's mother's mother's father's mother's mother's father's mother's mother's father's mother's mother's father's father's father's mother's father
Your father's father's father's father's father's father's mother's mother's father's mother's mother's father's mother's mother's father's mother's mother's father's father's father's mother's father, a 20x great-grandfather, is number 4250466.