Kinship Calculator: Find Cousin and Family Relationships

Find out how two people are related through a shared ancestor. Enter each generation distance to identify siblings, cousins, or cousins once removed.

Generations to the shared ancestor

Count parent links upward. Siblings = 1 + 1, first cousins = 2 + 2, parent and child = 0 + 1.

Person A links
Person B links
Quick examples

Labels and settings stay in this browser. No family data is uploaded.

Explore the family path

Click any node to inspect that step. The two columns meet at the shared ancestor.

Select a node to see what that step means.

Person A ↔ Person B: are cousins (degree 1).

4 parent links between themCollateral line

How this is calculated

Person A2 linksCommon ancestor

Person B2 linksCommon ancestor

Family-tree distance

4 parent links between them through this shared ancestor. 2 links + 2 links = 4 parent links between them.

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Frequently Asked Questions

How do I calculate the relationship between two people?

Choose an ancestor shared by both people, then count parent links from each person up to that ancestor. Enter the two counts and the calculator names the relationship.

What does 2 + 2 mean in a family tree?

Both people are two parent links from the same ancestor, so they are first cousins.

What does 2 + 3 mean?

The people are first cousins once removed. They share the same cousin line, but one person is one generation farther from the shared ancestor.

What does 0 mean?

A zero means that person is the shared ancestor itself. For example, 0 + 1 describes a parent and child.

Does this prove that two people are related?

No. The calculator classifies a family path you already provide. It does not verify records, discover ancestors, identify people, or decide legal inheritance.

Are names uploaded or stored online?

No. The interface runs in the browser and stores the current labels locally when local storage is available. You can use generic labels instead of names.

# Find the Relationship Between Two People

Use this kinship calculator when you already know the shared ancestor and want to name the relationship. Enter how many parent links separate each person from that ancestor. The calculator then identifies the family relationship and shows the path that leads to the answer.

# What the Generation Numbers Mean

  • 0 means the person is the shared ancestor.
  • 1 means the person is one parent link below the ancestor.
  • 2 means the person is a grandchild of the ancestor.
  • 3 means the person is a great-grandchild of the ancestor.

# Common Kinship Examples

  • 1 + 1 = siblings: both people are children of the same ancestor.
  • 2 + 2 = first cousins: both people are grandchildren of the same ancestor.
  • 2 + 3 = first cousins once removed: one branch is one generation farther away.
  • 0 + 1 = parent and child: one person is the shared ancestor of the other.
A relationship classifier instead of a family tree search
This tool does not discover ancestors, verify documents, identify people, or calculate inheritance rights. It classifies the path you provide, so use original records and the rules of the relevant jurisdiction for important decisions.

Bibliographic References