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
- 6967 Your mother's father's mother's mother's father's father's mother's mother's father's mother's mother's mother
- 13935 Your mother's father's mother's mother's father's father's mother's mother's father's mother's mother's mother's mother
- 27870 Your mother's father's mother's mother's father's father's mother's mother's father's mother's mother's mother's mother's father
- 55740 Your mother's father's mother's mother's father's father's mother's mother's father's mother's mother's mother's mother's father's father
- 111481 Your mother's father's mother's mother's father's father's mother's mother's father's mother's mother's mother's mother's father's father's mother
- 222963 Your mother's father's mother's mother's father's father's mother's mother's father's mother's mother's mother's mother's father's father's mother's mother
- 445926 Your mother's father's mother's mother's father's father's mother's mother's father's mother's mother's mother's mother's father's father's mother's mother's father
- 891853 Your mother's father's mother's mother's father's father's mother's mother's father's mother's mother's mother's mother's father's father's mother's mother's father's mother
- 1783706 Your mother's father's mother's mother's father's father's mother's mother's father's mother's mother's mother's mother's father's father's mother's mother's father's mother's father
- 3567413 Your mother's father's mother's mother's father's father's mother's mother's father's mother's mother's mother's mother's father's father's mother's mother's father's mother's father's mother
- 7134827 Your mother's father's mother's mother's father's father's mother's mother's father's mother's mother's mother's mother's father's father's mother's mother's father's mother's father's mother's mother
Your mother's father's mother's mother's father's father's mother's mother's father's mother's mother's mother's mother's father's father's mother's mother's father's mother's father's mother's mother, a 20x great-grandmother, is number 7134827.