Genealogy calculators

Family tree math: translate shared-ancestor generations into cousin labels, map birth years to generational cohorts (Pew-style ranges), and estimate how many ancestors you have N generations back with a pedigree-collapse caveat. Factual formulas — relationship labels follow standard genealogy convention.

Cousin terminology follows a rule that is simpler than its reputation. The number tells you how many generations separate you both from the shared ancestor: first cousins share grandparents, second cousins share great-grandparents. “Removed” counts the difference in generation between the two of you, so your first cousin’s child is your first cousin once removed rather than a second cousin. The ancestor count tool doubles each generation back — two parents, four grandparents, eight great-grandparents — which produces impossible numbers within about thirty generations, exceeding the human population of the time. The resolution is pedigree collapse: distant relatives marry, so the same ancestor occupies several positions in the tree and the true count of distinct individuals is far lower. Generational cohort ranges are journalistic conventions with no formal definition, and different institutions draw the boundaries differently.