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
- 16 Your father's father's father's father
- 33 Your father's father's father's father's mother
- 67 Your father's father's father's father's mother's mother
- 135 Your father's father's father's father's mother's mother's mother
- 270 Your father's father's father's father's mother's mother's mother's father
- 540 Your father's father's father's father's mother's mother's mother's father's father
- 1081 Your father's father's father's father's mother's mother's mother's father's father's mother
- 2163 Your father's father's father's father's mother's mother's mother's father's father's mother's mother
- 4326 Your father's father's father's father's mother's mother's mother's father's father's mother's mother's father
- 8653 Your father's father's father's father's mother's mother's mother's father's father's mother's mother's father's mother
- 17307 Your father's father's father's father's mother's mother's mother's father's father's mother's mother's father's mother's mother
- 34614 Your father's father's father's father's mother's mother's mother's father's father's mother's mother's father's mother's mother's father
- 69229 Your father's father's father's father's mother's mother's mother's father's father's mother's mother's father's mother's mother's father's mother
- 138459 Your father's father's father's father's mother's mother's mother's father's father's mother's mother's father's mother's mother's father's mother's mother
- 276918 Your father's father's father's father's mother'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
- 553837 Your father's father's father's father's mother'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
- 1107675 Your father's father's father's father's mother'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 mother
- 2215350 Your father's father's father's father's mother'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 mother's father
- 4430700 Your father's father's father's father's mother'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 mother's father's father
Your father's father's father's father's mother'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 mother's father's father, a 20x great-grandfather, is number 4430700.