This calculator names the relationship between two people when you know how many generations each one is from a shared ancestor. Enter the two counts: 1 for a child of the ancestor, 2 for a grandchild, and so on.
How the names work
Siblings are both one generation from their parents. First cousins are both two generations from their shared grandparents. Cousins who are not the same number of generations from the ancestor are “removed” by the difference: a first cousin once removed is two generations from the shared ancestor on one side and three on the other. Aunts, uncles, nieces and nephews appear when one person is one generation from the ancestor and the other is two or more.
Using it with the 1885 sketches
Many sketches in the 1885 book name parents, brothers and sisters. After finding a name with the surname search, use this calculator to describe how two people who share a grandparent are related.
The degree of a cousin relationship comes from the generation count to the shared ancestor. Take the smaller of the two counts and subtract one: with counts of 2 and 2 the result is first cousins, with 3 and 3 second cousins, with 4 and 4 third cousins. When the two counts differ, the difference is the number of times the cousins are “removed”. Counts of 2 and 4 give first cousins twice removed, because one person is two generations further from the shared ancestor than the other.
Half, step and in-law relatives
Half relatives share only one ancestor instead of a couple. Half-siblings share one parent, and half first cousins share one grandparent. The calculator gives the relationship through the shared ancestor, so for a half relationship add the word “half” to the answer. Step relatives and relatives by marriage are not blood relatives and are not calculated here, although a nineteenth-century sketch may use the same words for them.
Common mistakes
The most frequent error is counting the generations between the two people instead of counting each person’s distance from the shared ancestor. Another is to treat “second cousin” and “first cousin once removed” as the same relationship, although they are different. Birth order also matters: first cousins can be decades apart in age when the parents were born many years apart, so age alone does not show the degree.
Checking a result against records
A calculated relationship is only as reliable as the family tree behind it. Before stating a relationship in a family history, confirm each parent and child link in the census households, parish registers or civil registrations, and see the genealogy research checklist for where those records are held. The surname search shows who appears in the 1885 sketches, which often name a person’s father or sons.
Worked examples
1 and 1: siblings.
1 and 2: one is an aunt or uncle, the other a niece or nephew.
2 and 2: first cousins.
2 and 3: first cousins once removed.
3 and 3: second cousins.
2 and 4: first cousins twice removed.
The counts are the number of generations from the shared ancestor, so for the first cousins in the list both people are two generations below the same grandparents.