Free genealogy tool

Free Cousin Relationship Calculator

A cousin relationship calculator compares each person's distance from the same common ancestor to name the exact kinship between them. Use it to confirm whether two relatives are second cousins, once removed, siblings, or on the aunt-and-uncle branch.

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Use the calculatorTry Family Roots

How are we related calculator

Enter both relatives, label the shared ancestor, and compare how far each branch descends. The result updates instantly on the page with no server calls.

Client-side tool

Calculated relationship

Cousin

First cousin once removed

Removed tells you how many generations apart two relatives are while they stay in the same cousin line.

Person A is Person B's first cousin once removed.

Person B is Person A's first cousin once removed.

The smaller depth sets the cousin degree, and the generation gap between the two branches becomes the removal count.

Shared ancestor label
Shared ancestor
Great-grandparent generation ancestor
Formula
min(2, 3) - 1 = 1 for the cousin degree, and |2 - 3| = 1 for the removed count.

Want more than a quick answer?

Build the full tree inside Family Roots, invite relatives to collaborate, and keep the relationship history attached to real people instead of loose notes.

Explore Family RootsStart your tree

Visual branch diagram

Both branches start at Shared ancestor. The lower branch sets the removed count; the shallower matching branch sets the cousin degree.

Shared ancestorshared great-grandparent

Person A

1Child
2Person A

Person B

1Child
2Grandchild
3Person B

Mini cousin chart

Cross-reference both branches. The highlighted cell matches the live result above.

Rows: Person A • Columns: Person B
Cousin chart comparing Person A branch depth and Person B branch depth under the same common ancestor.
DepthChildGrandchildGreat-grandchild2x great3x great4x great5x great
ChildSiblingAunt/uncleGreat-aunt/uncle2x great-aunt/uncle3x great-aunt/uncle4x great-aunt/uncle5x great-aunt/uncle
GrandchildNiece/nephewFirst cousinFirst cousin once removedFirst cousin twice removedFirst cousin 3 times removedFirst cousin 4 times removedFirst cousin 5 times removed
Great-grandchildGreat-niece/nephewFirst cousin once removedSecond cousinSecond cousin once removedSecond cousin twice removedSecond cousin 3 times removedSecond cousin 4 times removed
2x great-grandchild2x great-niece/nephewFirst cousin twice removedSecond cousin once removedThird cousinThird cousin once removedThird cousin twice removedThird cousin 3 times removed
3x great-grandchild3x great-niece/nephewFirst cousin 3 times removedSecond cousin twice removedThird cousin once removedFourth cousinFourth cousin once removedFourth cousin twice removed
4x great-grandchild4x great-niece/nephewFirst cousin 4 times removedSecond cousin 3 times removedThird cousin twice removedFourth cousin once removedFifth cousinFifth cousin once removed
5x great-grandchild5x great-niece/nephewFirst cousin 5 times removedSecond cousin 4 times removedThird cousin 3 times removedFourth cousin twice removedFifth cousin once removedSixth cousin

How to use this cousin chart

The calculator works best when you know the nearest common ancestor shared by both people and can place each branch correctly below that person.

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  1. Step 1

    Enter both relatives

    Add two names so the result reads like a real family connection instead of generic labels.

  2. Step 2

    Label the shared ancestor

    Type the common ancestor's name and choose the ancestor generation label you want shown on the visual chart.

  3. Step 3

    Choose each branch depth

    Select how far each person is below that same ancestor, such as child, grandchild, or great-grandchild.

  4. Step 4

    Read the result and chart

    The calculator names the relationship, shows whether it is removed, and highlights the connection visually so you can verify the answer.

FAQ

Common questions about cousin relationships, shared ancestors, and how to interpret the result.

What does once removed mean?

Once removed means the two relatives are one generation apart while staying in the same cousin line. Your parent's first cousin and your first cousin's child are both your first cousin once removed.

How do I find my common ancestor?

Look for the nearest person who appears in both branches of your tree. That may be a grandparent, great-grandparent, or an earlier shared ancestor depending on how far back the connection goes.

What is the difference between second cousin and first cousin once removed?

Second cousins are in the same generation and share great-grandparents. First cousins once removed share grandparents but sit one generation apart from each other.

Can this family relationship calculator show aunts, uncles, and siblings too?

Yes. If one branch is still at the child level of the shared ancestor, the result becomes an aunt, uncle, niece, or nephew relationship. If both branches are children of the same ancestor, the result is siblings.

More Family Roots tools

Keep exploring your tree with other free tools inside the Family Roots toolkit.

Family Relationship Chart

Use a wider relationship matrix when you want to compare many cousin and side-branch scenarios quickly.

Family Tree Maker

Turn the relationship into a real tree you can save, expand, and share with relatives.

Generation Timeline Builder

See how multiple generations overlap in time once you know where each branch belongs.

Free Ancestry Name Origin Lookup

Research the surname roots behind the branches you are connecting in your family tree.