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
- 79 Your father's father's mother's mother's mother's mother
- 158 Your father's father's mother's mother's mother's mother's father
- 317 Your father's father's mother's mother's mother's mother's father's mother
- 635 Your father's father's mother's mother's mother's mother's father's mother's mother
- 1270 Your father's father's mother's mother's mother's mother's father's mother's mother's father
- 2541 Your father's father's mother's mother's mother's mother's father's mother's mother's father's mother
- 5083 Your father's father's mother's mother's mother's mother's father's mother's mother's father's mother's mother
- 10167 Your father's father's mother's mother's mother's mother's father's mother's mother's father's mother's mother's mother
- 20335 Your father's father's mother's mother's mother's mother's father's mother's mother's father's mother's mother's mother's mother
- 40670 Your father's father's mother's mother's mother's mother's father's mother's mother's father's mother's mother's mother's mother's father
- 81341 Your father's father's mother's mother's mother's mother's father's mother's mother's father's mother's mother's mother's mother's father's mother
- 162683 Your father's father's mother's mother's mother's mother's father's mother's mother's father's mother's mother's mother's mother's father's mother's mother
- 325367 Your father's father's mother's mother's mother's mother's father's mother's mother's father's mother's mother's mother's mother's father's mother's mother's mother
- 650735 Your father's father's mother's mother's mother's mother's father's mother's mother's father's mother's mother's mother's mother's father's mother's mother's mother's mother
- 1301471 Your father's father's mother's mother's mother's mother's father's mother's mother's father's mother's mother's mother's mother's father's mother's mother's mother's mother's mother
- 2602943 Your father's father's mother's mother's mother's mother's father's mother's mother's father's mother's mother's mother's mother's father's mother's mother's mother's mother's mother's mother
- 5205887 Your father's father's mother's mother's mother's mother's father's mother's mother's father's mother's mother's mother's mother's father's mother's mother's mother's mother's mother's mother's mother
- 10411775 Your father's father's mother's mother's mother's mother's father's mother's mother's father's mother's mother's mother's mother's father's mother's mother's mother's mother's mother's mother's mother's mother
- 20823550 Your father's father's mother's mother's mother's mother's father's mother's mother's father's mother's mother's mother's mother's father's mother's mother's mother's mother's mother's mother's mother's mother's father
Your father's father's mother's mother's mother's mother's father's mother's mother's father's mother's mother's mother's mother's father's mother's mother's mother's mother's mother's mother's mother's mother's father, a 22x great-grandfather, is number 20823550.