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
- 128 Your father's father's father's father's father's father's father
- 256 Your father's father's father's father's father's father's father's father
- 513 Your father's father's father's father's father's father's father's father's mother
- 1027 Your father's father's father's father's father's father's father's father's mother's mother
- 2054 Your father's father's father's father's father's father's father's father's mother's mother's father
- 4108 Your father's father's father's father's father's father's father's father's mother's mother's father's father
- 8217 Your father's father's father's father's father's father's father's father's mother's mother's father's father's mother
- 16435 Your father's father's father's father's father's father's father's father's mother's mother's father's father's mother's mother
- 32870 Your father's father's father's father's father's father's father's father's mother's mother's father's father's mother's mother's father
- 65740 Your father's father's father's father's father's father's father's father's mother's mother's father's father's mother's mother's father's father
- 131481 Your father's father's father's father's father's father's father's father's mother's mother's father's father's mother's mother's father's father's mother
- 262963 Your father's father's father's father's father's father's father's father's mother's mother's father's father's mother's mother's father's father's mother's mother
- 525926 Your father's father's father's father's father's father's father's father's mother's mother's father's father's mother's mother's father's father's mother's mother's father
- 1051852 Your father's father's father's father's father's father's father's father's mother's mother's father's father's mother's mother's father's father's mother's mother's father's father
- 2103705 Your father's father's father's father's father's father's father's father's mother's mother's father's father's mother's mother's father's father's mother's mother's father's father's mother
- 4207411 Your father's father's father's father's father's father's father's father's mother's mother's father's father's mother's mother's father's father's mother's mother's father's father's mother's mother
Your father's father's father's father's father's father's father's father's mother's mother's father's father's mother's mother's father's father's mother's mother's father's father's mother's mother, a 20x great-grandmother, is number 4207411.