Family Relationship Calculator
Enter how many generations each person is from their most recent common ancestor.
How this cousin calculator works
This cousin calculator uses the standard genealogy method for naming family relationships. You provide the number of generations from a shared ancestor for two people, and the tool translates that into relationship terms like first cousin, second cousin once removed, great-aunt, or grandchild.
It is especially useful when you are building a family tree and want quick, reliable labels without memorizing a full cousin chart.
How to count generations correctly
Step-by-step method
- Find the most recent common ancestor shared by both people.
- Count downward from that ancestor to Person A. That number is Person A's generation value.
- Count downward from that same ancestor to Person B. That number is Person B's generation value.
- Enter both values into the calculator.
Quick guide: child = 1, grandchild = 2, great-grandchild = 3, and so on.
Understanding cousin degree
If both people are at least two generations from the common ancestor, they are cousins. The smaller generation number determines cousin degree:
- 2 and 2 → first cousins
- 3 and 3 → second cousins
- 4 and 4 → third cousins
In plain terms, cousin degree is always one less than the smaller generation count.
What “removed” means
“Removed” tells you whether two cousins are in different generations. The removed count equals the absolute difference between the two generation values:
- 3 and 4 → second cousins once removed
- 2 and 4 → first cousins twice removed
“Removed” does not mean emotionally distant. It only means generational offset.
Examples
Common use cases
- 1 and 1: siblings
- 1 and 2: aunt/uncle and niece/nephew
- 0 and 1: parent and child
- 0 and 3: great-grandparent and great-grandchild
- 3 and 5: second cousins twice removed
Why this is useful for genealogy
A consistent relationship calculator helps with:
- Organizing DNA match results
- Labeling people in ancestry records
- Explaining relationships at reunions
- Avoiding errors when mapping a family tree relationship chart
Whether you are a beginner or an experienced family historian, clear relationship labels save time and reduce confusion.
FAQ
Can this calculator identify half-cousins?
No. Half relationships depend on whether one or both shared ancestors are common, and that detail is not included in this simplified input method.
Does this work for “in-law” relationships?
No. In-law terms are based on marriage connections, not direct bloodline generation counts.
What if both numbers are zero?
That means both entries refer to the same individual, specifically the chosen common ancestor.