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Calcimator

Cousin Relationship Calculator

Determine the exact cousin degree and removal between two people based on their common ancestor.

About this calculator

Genealogists describe cousin relationships with two numbers: a degree (first cousin, second cousin, third cousin, and so on) and a "removed" count for when the two people sit at different generational distances from their shared ancestor. This calculator derives both from how many generations separate each person from the Common Ancestor Generation: cousin degree is one less than the SMALLER of the two generational distances, and times removed is the difference between them. Raising Person A Generation never lowers Cousin Degree -- moving Person A further from the common ancestor either raises the degree or leaves it unchanged, since the degree is capped by whichever of the two people sits closer to that ancestor.

Once Person A Generation reaches 5 (with the calculator's default Person B Generation of 5 and Common Ancestor Generation of 2), Cousin Degree stops changing entirely and holds steady at 2 for any further increase, because at that point Person B's fixed distance from the ancestor becomes the limiting factor instead. The Est. Shared DNA % figure is a rough halving-per- generation approximation (about 12.5% for first cousins, about 3.1% for second cousins), not a substitute for an actual DNA test -- real shared DNA varies around these averages due to the randomness of genetic recombination.

Inputs

Results

Cousin Degree

1

Times Removed

1

Generation Gap1
Relationship Code (1=sibling, 2=1st cousin, 3=2nd cousin…)2
Est. Shared DNA %6.25%
How to Use This Calculator
  1. Enter Person A's Generation and Person B's Generation (counting down from a common ancestor).
  2. Enter the Common Ancestor Generation to establish the shared lineage point.
  3. Review the Cousin Degree (first, second, third cousin, etc.) and Times Removed.
  4. Check the Estimated Shared DNA percentage to calibrate DNA match expectations.
  5. Use the Relationship Code to explain relationships accurately in family history narratives.

How the result changes with Person A Generation

Person A GenerationCousin DegreeTimes Removed
203
302
621
1025

What each input means

Person A Generation
Pedigree generation number of Person A, counting down from the top of your tree
Person B Generation
Pedigree generation number of Person B, on the same counting scheme as Person A
Common Ancestor Generation
Generation number of the most recent common ancestor, on the same scale as the two people above

How this is calculated

Worked example, using the default values

  1. Identify Input Parameters
    Person A Generation = 4, Person B Generation = 5, Common Ancestor Generation = 2 = 3 input(s) provided
  2. Calculate Cousin Degree
    Cousin Degree
    1 = 1
  3. Calculate Times Removed
    Times Removed
    1 = 1
  4. Calculate Generation Gap
    Generation Gap
    1 = 1
  5. Calculate Relationship Code
    Relationship Code
    2 = 2

Engine last updated . Checked against 4 independently-derived tests — how we verify calculators. Built by Paul Gunder, a software engineer, not a licensed financial, medical, or legal professional.

Frequently Asked Questions

Can moving Person A further from the common ancestor ever lower the cousin degree?

No. Cousin Degree is one less than the smaller of the two people's generational distances from the common ancestor, so increasing Person A Generation can only raise the degree or leave it unchanged -- it can never lower it, since the degree is capped by whichever person sits closer to the shared ancestor.

Why does the cousin degree stop increasing after a certain point?

Once Person A's distance from the common ancestor equals or exceeds Person B's distance, Person B becomes the limiting (smaller) distance, and Cousin Degree is capped by whichever of the two is smaller. Moving Person A even further away no longer changes which distance is smaller, so the degree holds steady.

What does 'times removed' actually mean?

Times Removed counts how many generations apart two cousins are from each other, even though they share the same common ancestor. First cousins are zero times removed (same generational distance from the ancestor); a "first cousin once removed" is one generation apart, such as your first cousin's child.

How reliable is the Est. Shared DNA % figure?

It's a rough average based on halving the shared DNA percentage with each added generation of separation -- about 12.5% for first cousins, about 3.1% for second cousins. Actual DNA test results vary meaningfully around these averages because DNA recombination during reproduction is random, so treat this as a ballpark expectation, not a diagnostic figure.

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