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
- 141 Your father's father's father's mother's mother's father's mother
- 282 Your father's father's father's mother's mother's father's mother's father
- 564 Your father's father's father's mother's mother's father's mother's father's father
- 1128 Your father's father's father's mother's mother's father's mother's father's father's father
- 2257 Your father's father's father's mother's mother's father's mother's father's father's father's mother
- 4515 Your father's father's father's mother's mother's father's mother's father's father's father's mother's mother
- 9030 Your father's father's father's mother's mother's father's mother's father's father's father's mother's mother's father
- 18060 Your father's father's father's mother's mother's father's mother's father's father's father's mother's mother's father's father
- 36120 Your father's father's father's mother's mother's father's mother's father's father's father's mother's mother's father's father's father
- 72240 Your father's father's father's mother's mother's father's mother's father's father's father's mother's mother's father's father's father's father
- 144480 Your father's father's father's mother's mother's father's mother's father's father's father's mother's mother's father's father's father's father's father
- 288961 Your father's father's father's mother's mother's father's mother's father's father's father's mother's mother's father's father's father's father's father's mother
- 577923 Your father's father's father's mother's mother's father's mother's father's father's father's mother's mother's father's father's father's father's father's mother's mother
- 1155846 Your father's father's father's mother's mother's father's mother's father's father's father's mother's mother's father's father's father's father's father's mother's mother's father
- 2311693 Your father's father's father's mother's mother's father's mother's father's father's father's mother's mother's father's father's father's father's father's mother's mother's father's mother
- 4623387 Your father's father's father's mother's mother's father's mother's father's father's father's mother's mother's father's father's father's father's father's mother's mother's father's mother's mother
Your father's father's father's mother's mother's father's mother's father's father's father's mother's mother's father's father's father's father's father's mother's mother's father's mother's mother, a 20x great-grandmother, is number 4623387.