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
- 17 Your father's father's father's mother
- 35 Your father's father's father's mother's mother
- 70 Your father's father's father's mother's mother's father
- 140 Your father's father's father's mother's mother's father's father
- 280 Your father's father's father's mother's mother's father's father's father
- 561 Your father's father's father's mother's mother's father's father's father's mother
- 1123 Your father's father's father's mother's mother's father's father's father's mother's mother
- 2247 Your father's father's father's mother's mother's father's father's father's mother's mother's mother
- 4495 Your father's father's father's mother's mother's father's father's father's mother's mother's mother's mother
- 8991 Your father's father's father's mother's mother's father's father's father's mother's mother's mother's mother's mother
- 17983 Your father's father's father's mother's mother's father's father's father's mother's mother's mother's mother's mother's mother
- 35967 Your father's father's father's mother's mother's father's father's father's mother's mother's mother's mother's mother's mother's mother
- 71934 Your father's father's father's mother's mother's father's father's father's mother's mother's mother's mother's mother's mother's mother's father
- 143868 Your father's father's father's mother's mother's father's father's father's mother's mother's mother's mother's mother's mother's mother's father's father
- 287737 Your father's father's father's mother's mother's father's father's father's mother's mother's mother's mother's mother's mother's mother's father's father's mother
- 575474 Your father's father's father's mother's mother's father's father's father's mother's mother's mother's mother's mother's mother's mother's father's father's mother's father
- 1150948 Your father's father's father's mother's mother's father's father's father's mother's mother's mother's mother's mother's mother's mother's father's father's mother's father's father
- 2301896 Your father's father's father's mother's mother's father's father's father's mother's mother's mother's mother's mother's mother's mother's father's father's mother's father's father's father
- 4603793 Your father's father's father's mother's mother's father's father's father's mother's mother's mother's mother's mother's mother's mother's father's father's mother's father's father's father's mother
Your father's father's father's mother's mother's father's father's father's mother's mother's mother's mother's mother's mother's mother's father's father's mother's father's father's father's mother, a 20x great-grandmother, is number 4603793.