Two rules explain every cousin relationship. Find the common ancestor you share, the closest person you both descend from, and count how many generations each of you is below them.
The cousin chart
Find what person A is to the common ancestor down the left side (child, grandchild…) and what person B is across the top. The box where they meet tells you what B is to A.
| Common ancestor's… | Child | Grandchild | Great-grandchild | 2× great-grandchild | 3× great-grandchild | 4× great-grandchild |
|---|---|---|---|---|---|---|
| Child | Brother or sister | Niece or nephew | Grandniece or grandnephew | Great-grandniece or -nephew | 2× great-grandniece or -nephew | 3× great-grandniece or -nephew |
| Grandchild | Aunt or uncle | 1st cousin | 1st cousin once removed | 1st cousin twice removed | 1st cousin 3 times removed | 1st cousin 4 times removed |
| Great-grandchild | Great-aunt or great-uncle | 1st cousin once removed | 2nd cousin | 2nd cousin once removed | 2nd cousin twice removed | 2nd cousin 3 times removed |
| 2× great-grandchild | Great-great-aunt or -uncle | 1st cousin twice removed | 2nd cousin once removed | 3rd cousin | 3rd cousin once removed | 3rd cousin twice removed |
| 3× great-grandchild | 3× great-aunt or -uncle | 1st cousin 3 times removed | 2nd cousin twice removed | 3rd cousin once removed | 4th cousin | 4th cousin once removed |
| 4× great-grandchild | 4× great-aunt or -uncle | 1st cousin 4 times removed | 2nd cousin 3 times removed | 3rd cousin twice removed | 4th cousin once removed | 5th cousin |
Rule 1: the number (first, second, third cousin)
If you are the same number of generations below the common ancestor, you are cousins of the same "degree": share grandparents and you are first cousins, share great-grandparents and you are second cousins, share great-great-grandparents and you are third cousins.
Rule 2: removed
"Removed" means you are in different generations. Your first cousin's child is your first cousin once removed, because they are one generation further from the shared grandparents than you. Their grandchild is your first cousin twice removed. The relationship works both ways: you are their first cousin once removed too.
Examples
- Your mother's first cousin is your first cousin once removed.
- Your parent's first cousin's child is your second cousin.
- Your grandparent's brother is your great-uncle (also called grand-uncle), and his grandchild is your second cousin.
Why it matters
Knowing the exact relationship helps you place relatives in your family tree, read old letters and records, and make sense of DNA matches, which are usually reported as estimated cousin relationships.
Ready to draw your own tree? Open the family tree maker or print a free template.