Cousin Relationship Calculator

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Cousin Calculator

Count each person’s generations from the nearest ancestor the two share — a child is 1 generation, a grandchild 2, and so on — and enter both counts. Or click a row and a column in the table; Show Table brings it up if it is hidden.

A ↓ / B →ChildGrandchildGreat- Grandchild2x Great- Grandchild3x Great- Grandchild4x Great- Grandchild5x Great- Grandchild
ChildCommon AncestorAunt / Uncle Niece / NephewGreat- Aunt / Uncle Niece / Nephew2x Great- Aunt / Uncle Niece / Nephew3x Great- Aunt / Uncle Niece / Nephew4x Great- Aunt / Uncle Niece / Nephew5x Great- Aunt / Uncle Niece / Nephew
GrandchildAunt / Uncle Niece / Nephew1st cousin1st cousin, 1x removed1st cousin, 2x removed1st cousin, 3x removed1st cousin, 4x removed1st cousin, 5x removed
Great- GrandchildGreat- Aunt / Uncle Niece / Nephew1st cousin, 1x removed2nd cousin2nd cousin, 1x removed2nd cousin, 2x removed2nd cousin, 3x removed2nd cousin, 4x removed
2x Great- Grandchild2x Great- Aunt / Uncle Niece / Nephew1st cousin, 2x removed2nd cousin, 1x removed3rd cousin3rd cousin, 1x removed3rd cousin, 2x removed3rd cousin, 3x removed
3x Great- Grandchild3x Great- Aunt / Uncle Niece / Nephew1st cousin, 3x removed2nd cousin, 2x removed3rd cousin, 1x removed4th cousin4th cousin, 1x removed4th cousin, 2x removed
4x Great- Grandchild4x Great- Aunt / Uncle Niece / Nephew1st cousin, 4x removed2nd cousin, 3x removed3rd cousin, 2x removed4th cousin, 1x removed5th cousin5th cousin, 1x removed
5x Great- Grandchild5x Great- Aunt / Uncle Niece / Nephew1st cousin, 5x removed2nd cousin, 4x removed3rd cousin, 3x removed4th cousin, 2x removed5th cousin, 1x removed6th cousin

Cousin Calculator

Determine the cousin relationship between two people from how many generations each is from their nearest common ancestor. Enter the two counts, or pick a row and a column in the chart, and the result names the relationship — first cousins, second cousins once removed — and the generation each person stands at.

The chart also works in reverse: click the cell for a relationship found in a record, “second cousin once removed,” to see how many generations down from their shared ancestor each is. It shows every combination out to seven generations and can be extended further.

Counting generations

What generation should I enter?

A child is 1 generation from the common ancestor, a grandchild is 2, a great-grandchild is 3, a great-great-grandchild is 4, and so on. Each additional “great” adds 1. Count from the nearest ancestor the two people share: counting from a more distant one raises both numbers and overstates the relationship by a degree.

How should half relationships be handled?

The common ancestor in the chart is a couple who are both biological ancestors. Where two people descend from the same man but different women, or the same woman but different men, they share one biological ancestor rather than two and are half-cousins of the corresponding degree. The counting is identical; the prefix records that half the ancestry is not shared. Older records and most family usage drop the prefix, which is worth remembering when two lines apparently converge on a single name.

Degree and removal

What is a second (or third) cousin?

The number before “cousin” comes from the smaller generation count from the common ancestor, minus one. This is because a count of 1 is a child of the common ancestor, whose relationship to anyone else in the line is sibling, aunt or uncle, or great-aunt or great-uncle — not cousin. Two people who are both 2 generations from the common ancestor are first cousins; 3 generations down, second cousins; 4 generations down, third cousins.

What does it mean to be cousins once removed?

Removal is the difference between the two individuals’ generation counts from the common ancestor. When both are on the same generation, there is no removal at all. A person’s first cousin once removed is either their parent’s first cousin or their first cousin’s child: the same phrase, one generation up or one generation down. Records that use the phrase without qualification leave that direction to be worked out from ages.

Using the chart

Does it matter which person is A and which is B?

No. Degree and removal come out the same whichever way round the two counts are entered.

How far does the chart go?

It opens at seven generations down each side. The button beneath it adds three more at a time, and the two entry boxes accept any number, so a relationship beyond the chart’s edge can still be worked out.