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
- 6 Your mother's father
- 13 Your mother's father's mother
- 27 Your mother's father's mother's mother
- 54 Your mother's father's mother's mother's father
- 108 Your mother's father's mother's mother's father's father
- 217 Your mother's father's mother's mother's father's father's mother
- 435 Your mother's father's mother's mother's father's father's mother's mother
- 870 Your mother's father's mother's mother's father's father's mother's mother's father
- 1741 Your mother's father's mother's mother's father's father's mother's mother's father's mother
- 3483 Your mother's father's mother's mother's father's father's mother's mother's father's mother's mother
- 6966 Your mother's father's mother's mother's father's father's mother's mother's father's mother's mother's father
- 13933 Your mother's father's mother's mother's father's father's mother's mother's father's mother's mother's father's mother
- 27867 Your mother's father's mother's mother's father's father's mother's mother's father's mother's mother's father's mother's mother
- 55734 Your mother's father's mother's mother's father's father's mother's mother's father's mother's mother's father's mother's mother's father
- 111469 Your mother's father's mother's mother's father's father's mother's mother's father's mother's mother's father's mother's mother's father's mother
- 222938 Your mother's father's mother's mother'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 father
- 445877 Your mother's father's mother's mother'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 father's mother
- 891755 Your mother's father's mother's mother'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 father's mother's mother
- 1783510 Your mother's father's mother's mother'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 father's mother's mother's father
- 3567020 Your mother's father's mother's mother'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 father's mother's mother's father's father
- 7134040 Your mother's father's mother's mother'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 father's mother's mother's father's father's father
Your mother's father's mother's mother'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 father's mother's mother's father's father's father, a 20x great-grandfather, is number 7134040.