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Cousin & kinship calculator

Enter how many generations back your shared ancestor is for each person to find your exact relationship — 1st cousin, once removed, great-aunt, and more.

Parent = 1, grandparent = 2, great-grandparent = 3…

Same counting: parent = 1, grandparent = 2…

Shared ancestor
2 gens
Person A
3 gens
Person B
1st cousins, once removed

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How cousin terms work

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The cousin number

The cousin degree (1st, 2nd, 3rd…) is one less than the fewest generations back to your shared ancestor — first cousins share a grandparent, second cousins share a great-grandparent.

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"Removed" is a generation gap

If one side has more generations back to the ancestor than the other, you're cousins "removed" by that difference — once removed for 1 generation, twice for 2, and so on.

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When it's not a "cousin"

If the shared ancestor is only 1 generation back for one person, that person is the other's aunt, uncle, niece or nephew instead — or a direct parent/grandparent if it's 0 generations back for one side.

Cousin calculator FAQ

What does "once removed" mean?

"Removed" describes a generation gap between cousins. If your shared ancestor is your grandparent (2 generations) and their great-grandparent (3 generations), you're first cousins once removed — the "once" is the 1-generation difference.

What's a second cousin?

Second cousins share a great-grandparent (3 generations back for both people) rather than a grandparent. The cousin number is one less than the generations back to the shared ancestor.

How do I count generations to the shared ancestor?

Count parent-steps from each person to the shared ancestor: your parent is 1, grandparent is 2, great-grandparent is 3, and so on.